I've got a problem with the Start Menu and the Windows key on the keyboard, while in the 'Boris' profile. (The other profile is 'Test', which works fine.)
Windows 11 Home, 25H2, 26200.9457. Updates show up to date.
Whenever I left click on the Start Menu icon in the task bar, or I press
the Windows key on the keyboard, the window with all the apps appears, but immediately disappears, and the desktop reappears.
Anyone have any clues?
Thanks.
Open Services on Windows and change Macrium Service from Auto toManual, then stop the service. For most users, this is the only Macrium service that needs to be present, but not running in Automatic mode(in
Re-register the associated Macrium dll files
On Wed, 10/7/2026 1:05 AM, Boris wrote:
I've got a problem with the Start Menu and the Windows key on the
keyboard, while in the 'Boris' profile. (The other profile is 'Test',
which works fine.)
Windows 11 Home, 25H2, 26200.9457. Updates show up to date.
Whenever I left click on the Start Menu icon in the task bar, or I
press the Windows key on the keyboard, the window with all the apps
appears, but immediately disappears, and the desktop reappears. The
desktop then blinks five times, erasing itself and reappearing, every
five or so seconds, each time with the cursor pointing at that little
blue circle which rotates until the the next time the desktop
reappears. Then we're back to 'normal'.
The problem is that I can't click on any programs in the app menu,
because it disappears. Even if I can click on an app, such as
Calculator, Clock, or Notepad, noting happens, and the app window
disappears.
Here's the order that I ran some checks:
DISM....CheckHelath, took 20 minutes, completed successfully.
sfc /scannow; Windows Resourse Protection did not find any integrity
violations
DISM ....ScanHealth, ran relativeyl fast, ressult was 'the component
store is repairable'
DISm.... RestoreHealth, took 20 minutes, the restore operation
completed successfully
I also have another profile, called "Test".
If when in the Boris profile, which is the one giving me headaches, I
do a CRL-ALT-Del to get to the Test profile, all works just fine.
Anyone have any clues?
Thanks.
I wanted to get some idea of what the components are in the stack,
before going further. You can see because the answer involved "HKCU"
the Current User, that there is room for the Profile aspect
to your observations. Changing what running Profile is involved,
would present a different chunk of HKCU ?
**************************** CoPilot Question *********************************
A user has the following problem description. The operating system is
Windows 11.
Whenever I left click on the Start Menu icon in the task bar, or I press
the Windows key on the keyboard, the window with all the apps appears,
but immediately disappears, and the desktop reappears. The desktop then blinks five times, erasing itself and reappearing, every five or so
seconds, each time with the cursor pointing at that little blue circle
which rotates until the the next time the desktop reappears. Then we're
back to 'normal'.
Have you seen this symptom set before ?
The person asking the question has already tried DISM/SFC but I would
prefer to understand what software stack and applications are involved (ShellExperienceHost?).
It almost sounds like a fight between DWM and whatever hosts the Start
menu.
**************************** CoPilot Answer
*********************************
Short version: yes — I’ve seen this exact symptom cluster before,
and it almost always traces back to **ShellExperienceHost.exe crashing
or being repeatedly terminated**, often because something upstream in
the **WinUI/ImmersiveShell pipeline** is failing. The five‑blink
desktop redraw cycle is the giveaway: that's **Explorer.exe's visual
tree being torn down and rebuilt** after a shell component crash.
Let me give you a clean, architecture‑level breakdown of what’s
actually involved when you click Start, and then map your user’s
symptoms to the specific failure points.
---
## What components are involved when Start is invoked?
### **1. Explorer.exe**
- Owns the taskbar, Start button hit‑testing, and dispatches the "show Start" request. - If Explorer restarts, the desktop redraws (your "five blinks" symptom).
### **2. ShellExperienceHost.exe**
- The actual host for the Start menu, Action Center, calendar flyout,
volume flyout, etc. - A UWP-style process running under `C:\Windows\SystemApps\ShellExperienceHost_cw5n1h2txyewy`. - If this
crashes immediately after launch, Start will appear for a split second
then vanish.
### **3. StartMenuExperienceHost.exe**
- Dedicated host for the Start menu UI since Windows 10 1903.
- If this crashes, Start disappears instantly, but Explorer usually
stays alive.
### **4. SearchHost.exe**
- Handles the search box and search UI.
- If it’s misbehaving, Start may open but the search portion fails.
### **5. DWM.exe**
- Composes the desktop.
- If DWM is restarting, you get screen flicker - but **not** the
"desktop icons disappear
then reappear" pattern. That pattern is Explorer, not DWM.
### **6. WinUI / XAML islands**
- Start is a WinUI/XAML surface hosted inside ShellExperienceHost.
- Corruption in WinUI runtime packages can cause instant crashes.
### **7. AppX Deployment Service (AppXSVC)**
- If AppX packages for ShellExperienceHost or StartMenuExperienceHost
are damaged,
the host processes crash on launch.
---
## Mapping the user’s symptoms to the stack
### **Symptom 1: Start menu appears then instantly disappears**
This is classic **StartMenuExperienceHost.exe crash-on-launch**.
The window appears because the process *does* start, but the XAML
surface fails to initialize, causing the host to terminate.
### **Symptom 2: Desktop blinks five times**
This is **Explorer.exe restarting repeatedly**.
Explorer restarts when:
- A shell component crashes in a way that invalidates the visual tree
- A COM server that Explorer depends on fails activation
- A shell extension crashes Explorer
- ShellExperienceHost crashes in a tight loop
The "five blinks" is Explorer’s retry logic: it attempts to restart
the shell several times before giving up.
### **Symptom 3: Cursor shows the spinning blue circle during each
blink** That’s Explorer reloading:
- Desktop icons
- Taskbar
- Notification area
- Shell windows
This is not DWM. DWM flicker looks different (entire screen flashes
black or white).
---
## What causes this specific combination?
Here are the **top real-world causes** I’ve seen:
### **1. Corruption in ShellExperienceHost or StartMenuExperienceHost
AppX packages** This is the #1 cause.
Even if SFC/DISM report "no integrity violations", the AppX package
registry or deployment state can still be broken.
### **2. A broken or incompatible shell extension**
Explorer loads third‑party shell extensions at startup. If one crashes Explorer during Start invocation, you get the blink cycle.
Common offenders:
- Cloud storage clients (OneDrive, Dropbox, Box)
- Context menu extensions
- GPU control panel shell hooks
- Old WinRAR/7zip shell extensions
### **3. A bad ImmersiveShell registry state**
The Start menu depends on:
HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\StartPage HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\StartMenu
Corruption here can cause the host to crash immediately.
### **4. A failing AppX Deployment Service (AppXSVC)**
If AppXSVC is stuck or failing, StartMenuExperienceHost cannot load its resources.
### **5. GPU driver issues affecting WinUI surfaces**
Rare, but I’ve seen it:
- WinUI surfaces fail to initialize
- Host process crashes
- Explorer restarts trying to recover
### **6. Group Policy or registry hardening that disables UWP shell components** Seen in some enterprise environments.
---
## How to diagnose this properly (the right way)
### **1. Check Reliability Monitor** <=== perfmon /rel
Look for:
- ShellExperienceHost.exe
- StartMenuExperienceHost.exe
- Explorer.exe
- ApplicationFrameHost.exe
If you see repeated crashes, you’ve found the culprit.
### **2. Check Event Viewer → Application log**
Filter for:
- Faulting application name: ShellExperienceHost.exe
- Faulting application name: StartMenuExperienceHost.exe
- Faulting module name: Windows.UI.Xaml.dll
- Faulting module name: twinui.pcshell.dll
These are the usual suspects.
### **3. Check AppX package health**
Run:
Get-AppxPackage *ShellExperienceHost* | Select Name, PackageFullName Get-AppxPackage *StartMenuExperienceHost* | Select Name, PackageFullName
If either is missing or has an empty InstallLocation, that’s your
smoking gun.
### **4. Check shell extensions**
Use Sysinternals Autoruns --> Explorer tab.
Disable all non-Microsoft shell extensions and test Start.
### **5. Check if Explorer is actually restarting**
Open Event Viewer --> Windows Logs --> Application
Look for:
Faulting application name: explorer.exe
---
## The fixes that actually work (in real cases)
### **Fix 1: Re-register all shell AppX packages**
This is the nuclear option that fixes most cases:
Get-AppxPackage -AllUsers | Foreach {
Add-AppxPackage -DisableDevelopmentMode -Register
"$($_.InstallLocation)\AppXManifest.xml"
}
### **Fix 2: Reset ShellExperienceHost**
Get-AppxPackage *ShellExperienceHost* | Reset-AppxPackage
### **Fix 3: Reset StartMenuExperienceHost**
Get-AppxPackage *StartMenuExperienceHost* | Reset-AppxPackage
### **Fix 4: Disable third‑party shell extensions**
Autoruns --> Explorer tab --> uncheck everything non‑Microsoft.
### **Fix 5: Clear ImmersiveShell registry state**
Delete (or rename):
HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\StartPage
HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\StartMenu
Explorer will recreate them.
### **Fix 6: Reinstall WinUI/XAML runtime**
DISM /Online /Add-Capability /CapabilityName:Windows.UI.Xaml
---
## My diagnosis based on the symptoms you described
This is **not** DWM fighting Explorer.
This is **Explorer repeatedly restarting because ShellExperienceHost
or StartMenuExperienceHost is crashing immediately after launch**.
The "Start menu appears then disappears instantly" is the signature of StartMenuExperienceHost dying.
The "desktop blinks five times" is Explorer’s restart loop.
---
If you want, you can paste:
- Reliability Monitor critical events
- The Application log entries around the time of the Start invocation
- Output of `Get-AppxPackage *ShellExperienceHost*`
- Output of `Get-AppxPackage *StartMenuExperienceHost*`
I can pinpoint the exact failing module.
**************************** End: CoPilot Answer
***************************
Paul
Paul <nospam@needed.invalid> wrote in news:11a4pfb$2k5m0$1@dont-email.me:
On Wed, 10/7/2026 1:05 AM, Boris wrote:
I've got a problem with the Start Menu and the Windows key on the
keyboard, while in the 'Boris' profile. (The other profile is 'Test',
which works fine.)
Windows 11 Home, 25H2, 26200.9457. Updates show up to date.
Whenever I left click on the Start Menu icon in the task bar, or I
press the Windows key on the keyboard, the window with all the apps
appears, but immediately disappears, and the desktop reappears. The
desktop then blinks five times, erasing itself and reappearing, every
five or so seconds, each time with the cursor pointing at that little
blue circle which rotates until the the next time the desktop
reappears. Then we're back to 'normal'.
The problem is that I can't click on any programs in the app menu,
because it disappears. Even if I can click on an app, such as
Calculator, Clock, or Notepad, noting happens, and the app window
disappears.
Here's the order that I ran some checks:
DISM....CheckHelath, took 20 minutes, completed successfully.
sfc /scannow; Windows Resourse Protection did not find any integrity
violations
DISM ....ScanHealth, ran relativeyl fast, ressult was 'the component
store is repairable'
DISm.... RestoreHealth, took 20 minutes, the restore operation
completed successfully
I also have another profile, called "Test".
If when in the Boris profile, which is the one giving me headaches, I
do a CRL-ALT-Del to get to the Test profile, all works just fine.
Anyone have any clues?
Thanks.
I wanted to get some idea of what the components are in the stack,
before going further. You can see because the answer involved "HKCU"
the Current User, that there is room for the Profile aspect
to your observations. Changing what running Profile is involved,
would present a different chunk of HKCU ?
**************************** CoPilot Question
*********************************
A user has the following problem description. The operating system is
Windows 11.
Whenever I left click on the Start Menu icon in the task bar, or I press
the Windows key on the keyboard, the window with all the apps appears,
but immediately disappears, and the desktop reappears. The desktop then
blinks five times, erasing itself and reappearing, every five or so
seconds, each time with the cursor pointing at that little blue circle
which rotates until the the next time the desktop reappears. Then we're
back to 'normal'.
Have you seen this symptom set before ?
The person asking the question has already tried DISM/SFC but I would
prefer to understand what software stack and applications are involved
(ShellExperienceHost?).
It almost sounds like a fight between DWM and whatever hosts the Start
menu.
**************************** CoPilot Answer
*********************************
Short version: yes — I’ve seen this exact symptom cluster before,
and it almost always traces back to **ShellExperienceHost.exe crashing
or being repeatedly terminated**, often because something upstream in
the **WinUI/ImmersiveShell pipeline** is failing. The five‑blink
desktop redraw cycle is the giveaway: that's **Explorer.exe's visual
tree being torn down and rebuilt** after a shell component crash.
Let me give you a clean, architecture‑level breakdown of what’s
actually involved when you click Start, and then map your user’s
symptoms to the specific failure points.
---
## What components are involved when Start is invoked?
### **1. Explorer.exe**
- Owns the taskbar, Start button hit‑testing, and dispatches the "show
Start" request. - If Explorer restarts, the desktop redraws (your "five
blinks" symptom).
### **2. ShellExperienceHost.exe**
- The actual host for the Start menu, Action Center, calendar flyout,
volume flyout, etc. - A UWP-style process running under
`C:\Windows\SystemApps\ShellExperienceHost_cw5n1h2txyewy`. - If this
crashes immediately after launch, Start will appear for a split second
then vanish.
### **3. StartMenuExperienceHost.exe**
- Dedicated host for the Start menu UI since Windows 10 1903.
- If this crashes, Start disappears instantly, but Explorer usually
stays alive.
### **4. SearchHost.exe**
- Handles the search box and search UI.
- If it’s misbehaving, Start may open but the search portion fails. >>
### **5. DWM.exe**
- Composes the desktop.
- If DWM is restarting, you get screen flicker - but **not** the
"desktop icons disappear
then reappear" pattern. That pattern is Explorer, not DWM.
### **6. WinUI / XAML islands**
- Start is a WinUI/XAML surface hosted inside ShellExperienceHost.
- Corruption in WinUI runtime packages can cause instant crashes.
### **7. AppX Deployment Service (AppXSVC)**
- If AppX packages for ShellExperienceHost or StartMenuExperienceHost
are damaged,
the host processes crash on launch.
---
## Mapping the user’s symptoms to the stack
### **Symptom 1: Start menu appears then instantly disappears**
This is classic **StartMenuExperienceHost.exe crash-on-launch**.
The window appears because the process *does* start, but the XAML
surface fails to initialize, causing the host to terminate.
### **Symptom 2: Desktop blinks five times**
This is **Explorer.exe restarting repeatedly**.
Explorer restarts when:
- A shell component crashes in a way that invalidates the visual tree
- A COM server that Explorer depends on fails activation
- A shell extension crashes Explorer
- ShellExperienceHost crashes in a tight loop
The "five blinks" is Explorer’s retry logic: it attempts to restart >> the shell several times before giving up.
### **Symptom 3: Cursor shows the spinning blue circle during each
blink** That’s Explorer reloading:
- Desktop icons
- Taskbar
- Notification area
- Shell windows
This is not DWM. DWM flicker looks different (entire screen flashes
black or white).
---
## What causes this specific combination?
Here are the **top real-world causes** I’ve seen:
### **1. Corruption in ShellExperienceHost or StartMenuExperienceHost
AppX packages** This is the #1 cause.
Even if SFC/DISM report "no integrity violations", the AppX package
registry or deployment state can still be broken.
### **2. A broken or incompatible shell extension**
Explorer loads third‑party shell extensions at startup. If one crashes
Explorer during Start invocation, you get the blink cycle.
Common offenders:
- Cloud storage clients (OneDrive, Dropbox, Box)
- Context menu extensions
- GPU control panel shell hooks
- Old WinRAR/7zip shell extensions
### **3. A bad ImmersiveShell registry state**
The Start menu depends on:
HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\StartPage
HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\StartMenu
Corruption here can cause the host to crash immediately.
### **4. A failing AppX Deployment Service (AppXSVC)**
If AppXSVC is stuck or failing, StartMenuExperienceHost cannot load its
resources.
### **5. GPU driver issues affecting WinUI surfaces**
Rare, but I’ve seen it:
- WinUI surfaces fail to initialize
- Host process crashes
- Explorer restarts trying to recover
### **6. Group Policy or registry hardening that disables UWP shell
components** Seen in some enterprise environments.
---
## How to diagnose this properly (the right way)
### **1. Check Reliability Monitor** <=== perfmon /rel
Look for:
- ShellExperienceHost.exe
- StartMenuExperienceHost.exe
- Explorer.exe
- ApplicationFrameHost.exe
Reliability Monitor shows many StartMenuExperienceHost failures. This screenshot is of 9/21/2026, when this first started. This failure shows technical detail. (The desktop was not used again until yesterday,
10/6/2026, with the same failures, but there is no technical detail.
https://postimg.cc/BjCLJggT
If you see repeated crashes, you’ve found the culprit.
### **2. Check Event Viewer → Application log**
Filter for:
- Faulting application name: ShellExperienceHost.exe
- Faulting application name: StartMenuExperienceHost.exe
- Faulting module name: Windows.UI.Xaml.dll
- Faulting module name: twinui.pcshell.dll
These are the usual suspects.
### **3. Check AppX package health**
Run:
Get-AppxPackage *ShellExperienceHost* | Select Name, PackageFullName
Get-AppxPackage *StartMenuExperienceHost* | Select Name, PackageFullName
Result of above run in Powershell:
https://postimg.cc/mzKN7wKx
If either is missing or has an empty InstallLocation, that’s your
smoking gun.
### **4. Check shell extensions**
Use Sysinternals Autoruns --> Explorer tab.
Disable all non-Microsoft shell extensions and test Start.
### **5. Check if Explorer is actually restarting**
Open Event Viewer --> Windows Logs --> Application
Look for:
Faulting application name: explorer.exe
Event Viewer shows StartMenuExperienceHost failures.
https://postimg.cc/s1DvJ7s0
---
## The fixes that actually work (in real cases)
### **Fix 1: Re-register all shell AppX packages**
This is the nuclear option that fixes most cases:
Get-AppxPackage -AllUsers | Foreach {
Add-AppxPackage -DisableDevelopmentMode -Register
"$($_.InstallLocation)\AppXManifest.xml"
}
### **Fix 2: Reset ShellExperienceHost**
Applied this, no result
Get-AppxPackage *ShellExperienceHost* | Reset-AppxPackage
Applied this, no result
### **Fix 3: Reset StartMenuExperienceHost**
Get-AppxPackage *StartMenuExperienceHost* | Reset-AppxPackage
Applied this, no result
### **Fix 4: Disable third‑party shell extensions**
Autoruns --> Explorer tab --> uncheck everything non‑Microsoft.
### **Fix 5: Clear ImmersiveShell registry state**
Delete (or rename):
HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\StartPage
I renamed and restarted, 'StartPage' was rebuilt
HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\StartMenu
There was no 'StartMenu' in this location
Explorer will recreate them.
### **Fix 6: Reinstall WinUI/XAML runtime**
DISM /Online /Add-Capability /CapabilityName:Windows.UI.Xaml
---
## My diagnosis based on the symptoms you described
This is **not** DWM fighting Explorer.
This is **Explorer repeatedly restarting because ShellExperienceHost
or StartMenuExperienceHost is crashing immediately after launch**.
The "Start menu appears then disappears instantly" is the signature of
StartMenuExperienceHost dying.
The "desktop blinks five times" is Explorer’s restart loop.
This is exactly what is happening.
I'll have to keep investigating.
---
If you want, you can paste:
- Reliability Monitor critical events
- The Application log entries around the time of the Start invocation
- Output of `Get-AppxPackage *ShellExperienceHost*`
- Output of `Get-AppxPackage *StartMenuExperienceHost*`
I can pinpoint the exact failing module.
**************************** End: CoPilot Answer ***************************
On Wed, 10/7/2026 1:15 PM, Boris wrote:
Paul <nospam@needed.invalid> wrote in
news:11a4pfb$2k5m0$1@dont-email.me:
On Wed, 10/7/2026 1:05 AM, Boris wrote:
I've got a problem with the Start Menu and the Windows key on the
keyboard, while in the 'Boris' profile. (The other profile is
'Test', which works fine.)
Windows 11 Home, 25H2, 26200.9457. Updates show up to date.
Whenever I left click on the Start Menu icon in the task bar, or I
press the Windows key on the keyboard, the window with all the apps
appears, but immediately disappears, and the desktop reappears. The
desktop then blinks five times, erasing itself and reappearing, every
five or so seconds, each time with the cursor pointing at that little
blue circle which rotates until the the next time the desktop
reappears. Then we're back to 'normal'.
The problem is that I can't click on any programs in the app menu,
because it disappears. Even if I can click on an app, such as
Calculator, Clock, or Notepad, noting happens, and the app window
disappears.
Here's the order that I ran some checks:
DISM....CheckHelath, took 20 minutes, completed successfully.
sfc /scannow; Windows Resourse Protection did not find any integrity
violations
DISM ....ScanHealth, ran relativeyl fast, ressult was 'the component
store is repairable'
DISm.... RestoreHealth, took 20 minutes, the restore operation
completed successfully
I also have another profile, called "Test".
If when in the Boris profile, which is the one giving me headaches, I
do a CRL-ALT-Del to get to the Test profile, all works just fine.
Anyone have any clues?
Thanks.
I wanted to get some idea of what the components are in the stack,
before going further. You can see because the answer involved "HKCU"
the Current User, that there is room for the Profile aspect
to your observations. Changing what running Profile is involved,
would present a different chunk of HKCU ?
**************************** CoPilot Question
*********************************
A user has the following problem description. The operating system is
Windows 11.
Whenever I left click on the Start Menu icon in the task bar, or I
press the Windows key on the keyboard, the window with all the apps
appears, but immediately disappears, and the desktop reappears. The
desktop then blinks five times, erasing itself and reappearing, every
five or so seconds, each time with the cursor pointing at that little
blue circle which rotates until the the next time the desktop
reappears. Then we're back to 'normal'.
Have you seen this symptom set before ?
The person asking the question has already tried DISM/SFC but I would
prefer to understand what software stack and applications are involved
(ShellExperienceHost?).
It almost sounds like a fight between DWM and whatever hosts the Start
menu.
**************************** CoPilot Answer
*********************************
Short version: yes — I’ve seen this exact symptom
cluster before, and it almost always traces back to
**ShellExperienceHost.exe crashing or being repeatedly terminated**,
often because something upstream in the **WinUI/ImmersiveShell
pipeline** is failing. The five‑blink desktop redraw cycle is
the giveaway: that's **Explorer.exe's visual tree being torn down and
rebuilt** after a shell component crash.
Let me give you a clean, architecture‑level breakdown of
what’s actually involved when you click Start, and then map
your user’s symptoms to the specific failure points.
---
## What components are involved when Start is invoked?
### **1. Explorer.exe**
- Owns the taskbar, Start button hit‑testing, and dispatches
the "show Start" request. - If Explorer restarts, the desktop redraws
(your "five blinks" symptom).
### **2. ShellExperienceHost.exe**
- The actual host for the Start menu, Action Center, calendar flyout,
volume flyout, etc. - A UWP-style process running under
`C:\Windows\SystemApps\ShellExperienceHost_cw5n1h2txyewy`. - If this
crashes immediately after launch, Start will appear for a split second
then vanish.
### **3. StartMenuExperienceHost.exe**
- Dedicated host for the Start menu UI since Windows 10 1903.
- If this crashes, Start disappears instantly, but Explorer usually
stays alive.
### **4. SearchHost.exe**
- Handles the search box and search UI.
- If it’s misbehaving, Start may open but the search portion
fails.
### **5. DWM.exe**
- Composes the desktop.
- If DWM is restarting, you get screen flicker - but **not** the
"desktop icons disappear
then reappear" pattern. That pattern is Explorer, not DWM.
### **6. WinUI / XAML islands**
- Start is a WinUI/XAML surface hosted inside ShellExperienceHost.
- Corruption in WinUI runtime packages can cause instant crashes.
### **7. AppX Deployment Service (AppXSVC)**
- If AppX packages for ShellExperienceHost or StartMenuExperienceHost
are damaged,
the host processes crash on launch.
---
## Mapping the user’s symptoms to the stack
### **Symptom 1: Start menu appears then instantly disappears**
This is classic **StartMenuExperienceHost.exe crash-on-launch**.
The window appears because the process *does* start, but the XAML
surface fails to initialize, causing the host to terminate.
### **Symptom 2: Desktop blinks five times**
This is **Explorer.exe restarting repeatedly**.
Explorer restarts when:
- A shell component crashes in a way that invalidates the visual tree
- A COM server that Explorer depends on fails activation
- A shell extension crashes Explorer
- ShellExperienceHost crashes in a tight loop
The "five blinks" is Explorer’s retry logic: it attempts to
restart the shell several times before giving up.
### **Symptom 3: Cursor shows the spinning blue circle during each
blink** That’s Explorer reloading:
- Desktop icons
- Taskbar
- Notification area
- Shell windows
This is not DWM. DWM flicker looks different (entire screen flashes
black or white).
---
## What causes this specific combination?
Here are the **top real-world causes** I’ve seen:
### **1. Corruption in ShellExperienceHost or StartMenuExperienceHost
AppX packages** This is the #1 cause.
Even if SFC/DISM report "no integrity violations", the AppX package
registry or deployment state can still be broken.
### **2. A broken or incompatible shell extension**
Explorer loads third‑party shell extensions at startup. If one
crashes Explorer during Start invocation, you get the blink cycle.
Common offenders:
- Cloud storage clients (OneDrive, Dropbox, Box)
- Context menu extensions
- GPU control panel shell hooks
- Old WinRAR/7zip shell extensions
### **3. A bad ImmersiveShell registry state**
The Start menu depends on:
HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\StartPage
HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\StartMenu
Corruption here can cause the host to crash immediately.
### **4. A failing AppX Deployment Service (AppXSVC)**
If AppXSVC is stuck or failing, StartMenuExperienceHost cannot load
its resources.
### **5. GPU driver issues affecting WinUI surfaces**
Rare, but I’ve seen it:
- WinUI surfaces fail to initialize
- Host process crashes
- Explorer restarts trying to recover
### **6. Group Policy or registry hardening that disables UWP shell
components** Seen in some enterprise environments.
---
## How to diagnose this properly (the right way)
### **1. Check Reliability Monitor** <=== perfmon /rel
Look for:
- ShellExperienceHost.exe
- StartMenuExperienceHost.exe
- Explorer.exe
- ApplicationFrameHost.exe
Reliability Monitor shows many StartMenuExperienceHost failures. This
screenshot is of 9/21/2026, when this first started. This failure
shows technical detail. (The desktop was not used again until
yesterday, 10/6/2026, with the same failures, but there is no technical
detail.
https://postimg.cc/BjCLJggT
If you see repeated crashes, you’ve found the culprit.
### **2. Check Event Viewer → Application log**
Filter for:
- Faulting application name: ShellExperienceHost.exe
- Faulting application name: StartMenuExperienceHost.exe
- Faulting module name: Windows.UI.Xaml.dll
- Faulting module name: twinui.pcshell.dll
These are the usual suspects.
### **3. Check AppX package health**
Run:
Get-AppxPackage *ShellExperienceHost* | Select Name, PackageFullName
Get-AppxPackage *StartMenuExperienceHost* | Select Name,
PackageFullName
Result of above run in Powershell:
https://postimg.cc/mzKN7wKx
If either is missing or has an empty InstallLocation, that’s
your smoking gun.
### **4. Check shell extensions**
Use Sysinternals Autoruns --> Explorer tab.
Disable all non-Microsoft shell extensions and test Start.
### **5. Check if Explorer is actually restarting**
Open Event Viewer --> Windows Logs --> Application
Look for:
Faulting application name: explorer.exe
Event Viewer shows StartMenuExperienceHost failures.
https://postimg.cc/s1DvJ7s0
---
## The fixes that actually work (in real cases)
### **Fix 1: Re-register all shell AppX packages**
This is the nuclear option that fixes most cases:
Get-AppxPackage -AllUsers | Foreach {
Add-AppxPackage -DisableDevelopmentMode -Register
"$($_.InstallLocation)\AppXManifest.xml"
}
### **Fix 2: Reset ShellExperienceHost**
Applied this, no result
Get-AppxPackage *ShellExperienceHost* | Reset-AppxPackage
Applied this, no result
### **Fix 3: Reset StartMenuExperienceHost**
Get-AppxPackage *StartMenuExperienceHost* | Reset-AppxPackage
Applied this, no result
### **Fix 4: Disable third‑party shell extensions**
Autoruns --> Explorer tab --> uncheck everything non‑Microsoft.
### **Fix 5: Clear ImmersiveShell registry state**
Delete (or rename):
HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\StartPage
I renamed and restarted, 'StartPage' was rebuilt
HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\StartMenu
There was no 'StartMenu' in this location
Explorer will recreate them.
### **Fix 6: Reinstall WinUI/XAML runtime**
DISM /Online /Add-Capability /CapabilityName:Windows.UI.Xaml
---
## My diagnosis based on the symptoms you described
This is **not** DWM fighting Explorer.
This is **Explorer repeatedly restarting because ShellExperienceHost
or StartMenuExperienceHost is crashing immediately after launch**.
The "Start menu appears then disappears instantly" is the signature of
StartMenuExperienceHost dying.
The "desktop blinks five times" is Explorer’s restart loop.
This is exactly what is happening.
I'll have to keep investigating.
---
If you want, you can paste:
- Reliability Monitor critical events
- The Application log entries around the time of the Start invocation
- Output of `Get-AppxPackage *ShellExperienceHost*`
- Output of `Get-AppxPackage *StartMenuExperienceHost*`
I can pinpoint the exact failing module.
**************************** End: CoPilot Answer
***************************
I was interested in this part. That's because your other profile had no problem working, so it is not an "OS level" issue. The executable files,
like a StartMenuExperienceHost kit, should be the same kit for both BadProfile and GoodProfile.
The Start menu depends on:
HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\StartPage
HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\StartMenu
*******
I tried a Google using your crash dump report, and there are a couple mentions of a Macrium complication. My Google search string was this:
StartMenuExperienceHost.exe Exception code: 0xc000071f Faulting
module path: C:\WINDOWS\SYSTEM32\ntdll.dll
and one link returned was this:
https://www.elevenforum.com/t/start-menu-is-crashing.46258/
My guesstimate. It's a shellex side effect, or something related to a
Macrium program file.
psmounterex.sys
of "Microsoft Vulnerable Driver Blocklist" fame
Your normal profile, you have Macrium 8 installed "just for you".
The Test profile, you cannot see Macrium 8 in your start menu there.
For this assumption to hold good water, Macrium is not installed for
the Test profile. Since your symptoms are differential, we need
a detectable difference, between the main profile and the test profile.
PSMounterex.sys is related to the right-click menu entry (a shellex),
that mounts MRIMG files and makes the volume inside visible on the
desktop. It should be blocked by Windows Defender, and not as a malware,
but via the vulnerable driver list. Your Test profile does not have that context menu entry.
If I want to mount an MRIMG now (not a restore, just a "look-see"),
I can do it on my Win7 machine across the room. I think doing
restores via the main program of Macrium, still works on this machine.
As for the range of Macrium which is blacklisted, it would be
more than Macrium 8, and when I got the dialog from Windows Defender,
I was running Macrium 7.
Anyway, maybe that will give you some ideas. That means, in addition
to the LLM-AI determination of the three keys, there is some
dependency, somehow, in an Explorer shellex causing PSMounterex.sys
to get sniffed or something.
And the theory holds more water, if you don't have Macrium 8
showing up in the Test profile.
Paul
On 10/07/2026 1:05 AM, Boris wrote:
I've got a problem with the Start Menu and the Windows key on the
keyboard, while in the 'Boris' profile. (The other profile is 'Test',
which works fine.)
Windows 11 Home, 25H2, 26200.9457. Updates show up to date.
Whenever I left click on the Start Menu icon in the task bar, or I
press the Windows key on the keyboard, the window with all the apps
appears, but immediately disappears, and the desktop reappears.
Anyone have any clues?
Thanks.
Windows 10/11 Work around
=> Disable the Personalization/Start option
Win11 – ‘Show recommended files in Start, recent files in File
Explorer and items in Jump Lists’
i.e. Disabling the above option may restore the Start Menu
*open/immediately close problem* and restore ‘clickable’
functionality of pinned items and user created groups and groups’
pinned items
It could also be 3rd party software related when Macrium Reflect(free or
fee) is present and it's processes are running at Startup and/or dll
files need re-registering
Open Services on Windows and change Macrium Service from Auto toManual, then stop the service. For most users, this is the only Macrium service that needs to be present, but not running in Automatic mode(in Manual mode, it will start when Macrium is opened and/or a choice is
made for imaging(3 choices - Disks, Partitions, File/Folder)
Re-register the associated Macrium dll files
Command Prompt, and select Run as administrator.
Navigate to the Macrium installation folder by running the following command:
cd "C:\Program Files\Macrium\Reflect"
Run the following commands one by one to re-register the extension
files: regsvr32 RContextMenu.dll
regsvr32 RShellEx.dll
You should receive a "DllRegisterServer... succeeded" message for
each command.
After making any of the above changes..
Restart your computer or restart Windows Explorer via Task Manager
for the changes to take effect.
I have Macrium 8 free.
Task Manager shows MacriumService.exe running in both the good and bad profiles, so I wasn't keen on uninstalling Macrium 8.
"....winston" <winstonmvp@gmail.com> wrote in news:11a5sq3$31ccg$1@dont-email.me:
On 10/07/2026 1:05 AM, Boris wrote:
I've got a problem with the Start Menu and the Windows key on the
keyboard, while in the 'Boris' profile. (The other profile is 'Test',
which works fine.)
Windows 11 Home, 25H2, 26200.9457. Updates show up to date.
Whenever I left click on the Start Menu icon in the task bar, or I
press the Windows key on the keyboard, the window with all the apps
appears, but immediately disappears, and the desktop reappears.
Anyone have any clues?
Thanks.
Windows 10/11 Work around
=> Disable the Personalization/Start option
Win11 – ‘Show recommended files in Start, recent files in File >> Explorer and items in Jump Lists’
i.e. Disabling the above option may restore the Start Menu
*open/immediately close problem* and restore ‘clickable’
functionality of pinned items and user created groups and groups’
pinned items
I went to Settings>Personalization>Start and disabled Pinned, Recent, and Jump lists. The Start Menu was now working properly.
I went back and enabled each item that I disabled, one by one, wanting to
see which, if not all, was responsible for 'fixing' the Start Menu. With each re-enabling, the Start Menu still worked. So, it could have been one,
or all together, that fixed the Start Menu.
By the way, in Paul's reply, which sent me to
https://www.elevenforum.com/t/start-menu-is-crashing.46258/
Poster Guru suggested Settings>Personalization>Start, and toggling
everything off, and then back on.
Thanks.
"....winston" <winstonmvp@gmail.com> wrote in news:11a5sq3$31ccg$1@dont-email.me:
On 10/07/2026 1:05 AM, Boris wrote:
I've got a problem with the Start Menu and the Windows key on the
keyboard, while in the 'Boris' profile. (The other profile is 'Test',
which works fine.)
Windows 11 Home, 25H2, 26200.9457. Updates show up to date.
Whenever I left click on the Start Menu icon in the task bar, or I
press the Windows key on the keyboard, the window with all the apps
appears, but immediately disappears, and the desktop reappears.
Anyone have any clues?
Thanks.
Windows 10/11 Work around
=> Disable the Personalization/Start option
Win11 – ‘Show recommended files in Start, recent files in File
Explorer and items in Jump Lists’
i.e. Disabling the above option may restore the Start Menu
*open/immediately close problem* and restore ‘clickable’
functionality of pinned items and user created groups and groups’
pinned items
I went to Settings>Personalization>Start and disabled Pinned, Recent, and Jump lists. The Start Menu was now working properly.
I went back and enabled each item that I disabled, one by one, wanting to
see which, if not all, was responsible for 'fixing' the Start Menu. With each re-enabling, the Start Menu still worked. So, it could have been one,
or all together, that fixed the Start Menu.
By the way, in Paul's reply, which sent me to
https://www.elevenforum.com/t/start-menu-is-crashing.46258/
Poster Guru suggested Settings>Personalization>Start, and toggling
everything off, and then back on.
Thanks.
It could also be 3rd party software related when Macrium Reflect(free or
fee) is present and it's processes are running at Startup and/or dll
files need re-registering
Open Services on Windows and change Macrium Service from Auto toManual, then stop the service. For most users, this is the only Macrium
service that needs to be present, but not running in Automatic mode(in
Manual mode, it will start when Macrium is opened and/or a choice is
made for imaging(3 choices - Disks, Partitions, File/Folder)
Re-register the associated Macrium dll files
Command Prompt, and select Run as administrator.
Navigate to the Macrium installation folder by running the following
command:
cd "C:\Program Files\Macrium\Reflect"
Run the following commands one by one to re-register the extension
files: regsvr32 RContextMenu.dll
regsvr32 RShellEx.dll
You should receive a "DllRegisterServer... succeeded" message for
each command.
After making any of the above changes..
Restart your computer or restart Windows Explorer via Task Manager
for the changes to take effect.
On 10/07/2026 5:28 PM, Boris wrote:
"....winston" <winstonmvp@gmail.com> wrote in
news:11a5sq3$31ccg$1@dont-email.me:
On 10/07/2026 1:05 AM, Boris wrote:
I've got a problem with the Start Menu and the Windows key on the
keyboard, while in the 'Boris' profile. (The other profile is
'Test', which works fine.)
Windows 11 Home, 25H2, 26200.9457. Updates show up to date.
Whenever I left click on the Start Menu icon in the task bar, or I
press the Windows key on the keyboard, the window with all the apps
appears, but immediately disappears, and the desktop reappears.
Anyone have any clues?
Thanks.
Windows 10/11 Work around
=> Disable the Personalization/Start option
Win11 – ‘Show recommended files in Start, recent files in File
Explorer and items in Jump Lists’
i.e. Disabling the above option may restore the Start Menu
*open/immediately close problem* and restore ‘clickable’
functionality of pinned items and user created groups and groups’
pinned items
I went to Settings>Personalization>Start and disabled Pinned, Recent,
and Jump lists. The Start Menu was now working properly.
I went back and enabled each item that I disabled, one by one, wanting
to see which, if not all, was responsible for 'fixing' the Start Menu.
With each re-enabling, the Start Menu still worked. So, it could have
been one, or all together, that fixed the Start Menu.
By the way, in Paul's reply, which sent me to
https://www.elevenforum.com/t/start-menu-is-crashing.46258/
Poster Guru suggested Settings>Personalization>Start, and toggling
everything off, and then back on.
Thanks.
It could also be 3rd party software related when Macrium Reflect(free
or fee) is present and it's processes are running at Startup and/or
dll files need re-registering
Open Services on Windows and change Macrium Service from Auto toManual, then stop the service. For most users, this is the only
Macrium service that needs to be present, but not running in Automatic
mode(in Manual mode, it will start when Macrium is opened and/or a
choice is made for imaging(3 choices - Disks, Partitions, File/Folder)
Re-register the associated Macrium dll files
Command Prompt, and select Run as administrator.
Navigate to the Macrium installation folder by running the following
command:
cd "C:\Program Files\Macrium\Reflect"
Run the following commands one by one to re-register the extension
files: regsvr32 RContextMenu.dll
regsvr32 RShellEx.dll
You should receive a "DllRegisterServer... succeeded" message for
each command.
After making any of the above changes..
Restart your computer or restart Windows Explorer via Task Manager
for the changes to take effect.
This issue, from my usage and networking first appeared in managed devices(admin setup devices where the default for some users was to have those three items enabled on Win11 or the only two available items on Win10(Start Jump Lists and File Explorer Quick Access).
Like you the Start Menu worked after re-enabling those settings, but
admins reported the condition reappearing on Win11, not Win10. The belief(condition reappearing) at that time was related to rebuilding the cache storage of recent items.
Let us know, if re-enabling those items on your Win11 device causes the
same issue to reappear.
| Sysop: | Scott Duensing |
|---|---|
| Location: | Freeburg, IL, USA, Earth |
| Users: | 5 |
| Nodes: | 16 (0 / 16) |
| Uptime: | 497975:18:38 |
| Calls: | 8 |
| Messages: | 25,051 |