I have a DELL, with XP and the rest is in the computer description. I am not running any new games or anything, and have formatted the HD 4 times and done 5 installes of window with and without SP2. I just got an ATI 9600 pro 256mb video card, and when I enter anything graphics intensive, the computer shuts down without any errors,no blue screen, no disk check when I restart, no reboot. It is just like someone pushing the power button without me looking. I just got a 450w PSU, and this problem only happens with the ATI card. I am sending it back for a replacement just incase it is bad, but if the new one does the same thing, I am going to buy a new MB and case, to get away from this DELL Junk. As for the rest of the problems, I am going to be starting with all the stuff suggested. Let me know if you have any ideas on the shutdown. It is not the drivers either, becuase I have tried 5 different drivers for this card as well!