HELP! 7405GX random shutdown.

A couple years ago I got the Gateway 7405GX from Best Buy (with the 3 yr warranty). I've already had it in for case cracking, display problems, etc. and they've all been fixed. Now, however, the system shuts down at random points all by itself. Conditions are truly random - hot day, cold day, on battery, on AC, web browsing, word processing, gaming, doing nothing... There seems to be no common conditions for the shutdown. I've gone in and turned OFF all power save options, am not overclocking anything, blew out the dust, and even installed one of the flat notebook cooler devices underneath it. It doesn't do an organized shutdown either, it just shuts off. This can happen several times one day (6 times this morning), and not at all for a week or so, then it starts happening again. The only common thing is that right before it shuts down I can hear a fan (or the CD Drive?) spin up, but it's not temperature related as the computer is very cool. I've even rebuilt the system with the Gateway Recovery DVD to make sure it's not a software problem. It happened WHILE I was rebuilding it. I took it in to Best Buy and they ran it under a "stress test" for a couple days and couldn't get it to shut down, so they handed it back without sending it in.

Anyone have any ideas on what I should try next (other than take it back to Best Buy again, that is...)?

Thanks.

 

It is seems it is not caused by overheating. I think maybe there is a part short with MB when your use the computer, maybe you could press the k/b or some other locations to duplicate the failure symptom.