User Profile Hive Cleanup service helps to ensure user sessions are completely terminated when a user logs off. System processes and apps occasionally maintain connections to registry keys in user profile after a user logs off. In those cases the user session is prevented from completely ending. This can result in problems when using Roaming User Profiles in a server environment or when using locked profiles as implemented through Shared Computer Toolkit for Windows XP.
On Windows 2000 you can benefit from this service if the app event log shows event id 1000 where the message text indicates that the profile isn't unloading and that error is "Access is denied". On Windows XP and Server 2003 either event ids 1517 and 1524 indicate the same profile unload problem.
To accomplish this the service monitors for logged off users that still have registry hives loaded. When that happens the service determines which app have handles opened to hives and releases them. It logs the app name and what registry keys were left open. After this the system finishes unloading the profile.
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