Question : LSASS.EXE Shuts down PC

LSASS.exe causes the computer to shut down after 60 seconds. Oddly, this happens about once per week and only on 3 of our computers. I do not believe it is the Sasser worm since we are running XP Pro with SP3. We tried running the Sasser Removal Tool from MS just for giggles, but it did not find anything. Here are the details of the three computers...

HP 8710P
XP Pro w/SP3
Panda AV with latest definitions
Office 2007 w/SP1

Steps taken thus far...
1. Added LSASS.EXE to DEP exceptions
2. Re-imaged hard drive
3. Uninstalled and reinstalled Panda AV
4. Uninstalled and reinstalled SP3

There does not seem to be a pattern as to when it happens. Some say it happens when the computer is just sitting there not being worked on. Some say it happens when working in Outlook or Excel.

Any other ideas as to what it could be?

Answer : LSASS.EXE Shuts down PC

RootRepeal - RootRepeal - Rootkit Detector
http://rootrepeal.googlepages.com/

DL this as well, and under each Tab, scan, and look for hidden services/files/drivers/processes.....