System is a PowerSpec 8821 (can view at powerspec.com/systems/archives/system_archive.phtml?selection=8821). Orig 250W PS was turning off after I added a GeForce 7600 video card (after 6 months of running it fine, LOL). Now, I know the card needed a minimum 300W PS, but I ran it anyway. Time to upgrade, so, I replaced the factory 250W power supply with Cooler Master 500W power supply. Now when I tell windows to shut down, it goes all the way down... Windows completes its shutdown... the power clicks off... and then click!, it powers back up and restarts. No settings in CMOS, the registry, or windows were ever touched, just removed one PS and installed the other. I looked for APM options in CMOS, saw none other than the 4 sec delay on the power button. This is not an OS issue, but something else. ANY IDEAS???