Could be as simple as the AC dipped out for just too long, cosmic ray or "other."
2 Mo old HP 2.2 AMD Media Center shut down while watching streaming movie. The movie had to be buffered for approx half hour in order to keep from rebuffering. I had watched one part of 3 chapters and pc had been running for about 1 hr total time. I recently added video card and higher watt power supply to accomodate the vid card. I have watched literally 6 or more consecutive hrs before and no problems. Could it be a heat problem or was it just a random failure. The unit shut off just like i had used the on-off switch on the power supply. THe pc started up with no hitches immediately after the failure. The incident happened with no warning on screen at all. Could the vid card cause the failure if it were faulty?