intel quad core 4 gig of ram 750w power supply Windows XP pro The PC run fine and everything seems normal when I am using it. I have it set up to "Turn monitor off" after 20 minutes and when I let it sit over night it will not respond, I am forced to manually shut down by holding the power button. I have "Turn off hard disk" and "system standby" set to never. I have run a system stress test with both Everest and memtest and tested the power supply. I happens almost every time it sits with the monitor off for a while. I have tried running windows repair off the XP cd and still have the issue. Any suggestions would be greatly appreciated.