Hi everyone, I have been visiting this site for a long time. I just decide to post my problem hoping one of you experts can offering me some suggestions. I have a dell 8400, 128mb running on XP home edition. For the last 2 to 3 weeks, when I first turn on my computer, it will start booting normally for about 15 to 20 sec, than it will shut off by itself without any error messanges. I would restart again, but it will shut off again like before. Sometimes, if I try 3 or 4 restarts, it will stabilize, but next morning, same problem will repeat itself. I have considered virus, fan problem, software conflicts, but all are without resolution. I have just reformated my hard drive, but again this problem persists. I am currently not running any window programs just dell utilities. Thank you for reading this. If you have encountered this problem or have any suggestion on how to resolve this, I very much appreciate.