Brought this thread back since I started having the same issue again.
It had been working just fine the whole week and then this morning after turning it on five minutes later it shut off.
Hitting the power button didn't do anything.
Got pissed and stopped trying. Then tonight I got my XBL Arcade cd. Played Ms Pac-Man for almost an hour and turned it off.
Hour later started to play Halo 2 and it turned its self off again. Unplugged from the power strip and directly into the wall outlet. Still no.
Tried in the other room in the power strip and wall still wouldn't turn on.
Done some searching and I don't seem to be having any syptoms of a typical psu issue. It doesn't ask me to reset the date whenever it does this.
Anyway it seems random with no rhym or reason.
Anymore suggestions would be great. Thanks!