I've had the computer for over a year, no problems, and have had windows 7 installed and running fine for a couple months.  Yesterday it started to reboot on its own, and is not starting correctly from the reboot.  About one in 25 times it will start and run for 3-4 minutes, then reboot itself again.  I've unchecked auto restart, and have gone through the startup fix utility that comes up occasionally during the reboot.  Doesn't want to system restore more than a couple days ago.  Did memory check and it checks out fine.  Run Trend micro and c cleaner religiously.  Any ideas?  THANKS!