Microsoft User Profile Hive Cleanup Service description
Microsoft User Profile Hive Cleanup Service - A service to help with slow log off and unreconciled profile problems

On Windows 2000 the service deals with application event log event 1000 from source Userenv where the message indicates that the profile is not unloading and the error is "Access is denied". On Windows XP and Windows 2003 the equivalent events are 1517 and 1524 from source Userenv.

To accomplish this the service monitors for logged off users that still have hives loaded. When that happens the service determines which applications have handles opened to the hives and releases them. It logs the application name and what registry keys where left open. After this the system finishes unloading the profile

What's New in This Release:

If a user is logging off and the user profile hive is not unloading and UPHClean is stopped it is possible that a STOP CE could occur. To avoid this UPHClean delays has been modified to only complete its cleanup to when it is being uninstalled.

Fixed error in UPHClean that could cause STOP 93 when protected handles were closed.

Added registry setting DISABLEREGFLUSHKEY. This setting prevents user profile unload from causing a registry flush to disk. In some cases poor performance affecting user application in other sessions can occur from doing this flushing. The setting defaults to 0 which has no effect. Setting it to 1 prevents user profile unload from causing registry flushing.