I just went through the trouble of installing XP SP1 onto a PCI-E system. Then I updated windows and all drivers. Afterwards I went about installing avast antivirus, spybot S&D, regcleaner and ad-aware se personal. (please, let me know if I made a bad choice with these utilities) I updated and ran these programs successfully with no detections. Up to this point I had no problems other than the PCI-E issue, which surprized me because I've always ran into numerous errors with os installations. The next day I started up the computer (at a different location than it was originally setup) and went to install a game. I'd say around halfway through the install the computer shutdown and re-booted. When I say shutdown I don't mean the normal windows shutdown process, but as if it had been turned off by the power button. So, I decided to run my virus scan, adware, and spyware software. During the virus and spyware scans, the same thing happened as did during the install of the game. I'm almost sure I've eliminated any hardware problems by bench tests and re-seating video and memory cards and still getting the same results. Also, system and cpu temps are staying roughly between 88F and 98F, so I can't imagine these shutdowns to be caused by heat. The system doesn't shutdown like this while idle either. Any suggestions as to why this could be happening would be appreciated and I hope I provided enough info.