Microsoft says that a user profile can become corrupted if your antivirus software is scanning your PC while you try to log on, but it could also be caused by other things.
A quick fix can be to restart your PC, but if this doesn’t work you’ll need to restart again and boot into Safe mode. Do this by pressing F8 before you see the Windows loading screen and choosing Safe Mode from the menu that appears.
Safe Mode logs you into the built-in Windows administrator account, but you might find that some options don’t work.
Step 1. To fix the user profile, click Start and type regedit into the search box and press Enter.
Step 2. Registry Editor will launch and you need to navigate to the following key: HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionProfileList
Step 3. Click each S-1-5 folder and double-click the ProfileImagePath entry to find out which user account it relates to. (If your folder name ends with .bak or .ba follow .)
Step 4. Once you have located the folder for the corrupt profile (and it doesn’t have a .bak ending), double-click RefCount and change the Value data to 0 and click Ok.
Step 5. Now double-click on State and make sure the Value data is again 0 and click Ok.
Step 6. Close regedit and restart your PC. You should now be able to log into your account.
If you’re still unable to fix the problem and can’t log in, you might have to reinstall Windows.