5 minutes later it *finally* powers off
It happens to more machines that it should. I decided to see what the problem might be. I searched google, forums, and newsgroups for an answer. The biggest culprit is a problem unloading the current users profile.
This can happen when third party, or even Microsoft applications have not properly cleaned up when exiting. Windows will keep trying to unload the profile until Windows finally decides that it can't and should shutdown. Even if you find the application causing the problem - it may be impossible to do anything about it.
This is why Microsoft released the User Profile Hive Cleanup Service
This free utility automatically cleans up user profiles and prevents you from playing the timeout wait game.
Once you run the setup wizard it will look like the installer did nothing. If you open up your services list, you will see that a new service is running in the background:
The idea of this program is to reclaim resources when a task is finished (memory, handles, etc). It accomplishes this by monitoring for users to log off and verifying that unused resources are reclaimed. This approach is superior as it works for any known reason that profiles do not unload and also will keep working to address new unknown issues.
Now when you go to shutdown, logoff or restart it will happen within seconds. Instead of minutes.