Forum Discussion
Class not registered message when trying to access windows menu
Got a strange issue with mulitple machines that seems to be growing. When users try to access Office applications, the windows start menu or search they get a pop up stating "Class not registered" for Explorer.exe. A profile rebuild or renaming the NTUSER.DAT file will resolve the issue, but sometimes this is temporary. We have investigated any changes that may have occured such as Dell updates, Windows updates etc. but cannot seem to be able to find the smoking gun. Also, the user seems to lose access to their user profile registry hive as well. We have enabled the registry audit GPO to at least try to see what is making these changes, so this may be of some help. Thank you for your comments.
1 Reply
Hi, this usually points to Windows shell/app registration damage rather than the Start menu itself being the only problem, especially since it is happening on multiple machines.
I would start by checking what changed recently across those PCs: Windows update, Office update, security software, profile management, or GPO. Then try these on one affected test machine:
1. Open an elevated Command Prompt and run DISM /Online /Cleanup-Image /RestoreHealth, then sfc /scannow.
2. Test with a brand-new local or domain profile. If the new profile works, the issue is likely profile-related.
3. Check Event Viewer under Application and System at the exact time Explorer.exe shows "Class not registered".
4. If these are managed devices, temporarily test with security tools or shell-related GPOs removed from one machine.
Renaming NTUSER.DAT helping is a good clue that the user profile is involved, but because it is spreading, I would look for the common trigger rather than rebuilding profiles one by one.
