It seems with Windows 7 with SP1 the auto log out feature of the FOG service is restarting machines even if activity has occurred during the proposed time out.
I set the timeout for log out to 5 minutes and went about surfing around the web, and it would still shut down with mouse and keyboard inputs even up to the point where it started shutting the machine down.
The entry in the log reads:
8/11/2012 10:31 PM FOG::AutoLogOut restarting computer due to inactivity
Event Viewer reads:
The process C:\Windows\system32\wbem\wmiprvse.exe (ECH) has initiated the restart of computer ECH on behalf of user NT AUTHORITY\SYSTEM for the following reason: No title for this reason could be found
Reason Code: 0x80070015