Hi, yes the event log indicates an unexpected shutdown , yet logs no cause, if it is software then usually you expect an indication, so I agree with John sounds like hardware.
This little script shows all hidden startup items (inc tasks), will work on Vista Seven.You might be surprised at the volume of items look for system32\ Tasks. Save the .Vbs returned, to the %root% (C and the output will appear there as well,(opens in notepad) run the short version (ie say yes), or come back tomorrow...
The unexpected shutdowns are forced by me - pressing & holding power button because 10-15 min after boot, the system is INOP - blue circle on screen; mouse moves, but can't click on anything - very similar to an APPCRASH. The occurrence is infrequent and lasts <24 hours as the 6008 entries indicate.
The only scheduled task I can think of that's got that sort of long interval is the WAT update validation test (~90 days)
You can set the interval to a shorter time if you want to test it - or just see the last run time in the Scheduler.