Hello there!

For months, I was experiencing difficulties with Microsoft Windows 10 not shutting down properly. The system would hang indefinitely, displaying on the screen: «Shutting down...». The mouse cursor was still responsive and typical disk activity was ongoing. It felt as though the system was waiting for a task to finish. This problem was occurring in a seemingly random fashion, not on every shutdown. Debugging the problem was a slow process because of this.

I searched the Internet for various possible solutions to fix the shutdown problem. I went through the typical solutions, such as setting WaitToKillAppTimeout and HungAppTimeout to low values in HKEY_CURRENT_USER\Control Panel\Desktop. It did not help. I tried changing the page file size to a smaller one, because I suspected memory management issues. Nothing helped.

To better narrow down the possible causes, I decided to first log out of the user session and then shut down. After a few days, this revealed that it was a user session problem, not a shutdown problem. The system was sometimes hanging at session end. I looked in the Event Viewer for possible explanations. I found that winlogon.exe — the Windows Logon process — was crashing. It was crashing because of a module named verifier.dll. The verifier.dll file is a core component of Microsoft's Driver Verifier (and Application Verifier) utility, a built-in Windows diagnostic tool.

For some reason, I had the Verifier module attached to winlogon.exe. Upon further research, I suspect SecureUXTheme caused this in my case.

The solution was straight-forward:

• Open a command prompt and run: verifier /reset.
• In the Registry Editor, navigate to: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\winlogon.exe
• Remove the GlobalFlag and VerifierDLLs subkeys.

I hope this post will be useful to someone out there.