I am posting this as a fresh thread since I now know for sure what was causing my problems. This problem did not occur in XP, only in Vista. I had an external DVD drive. Vista would install ok. The installer would take forever, but would work. Then I would install some updates, some drivers, then bam instant power off. It didn't seem to matter what order I installed things in. Eventually it would happen, and once it did, it would keep happening. Just as it would boot up to the desktop, it would instantly power off. I tried changing out things like the PSU, memory, cpu, etc... None of that changed the pattern. Everytime it instantly powers off I would have to unplug the power supply and wait a few minutes before I could turn it back on. So I decided to try putting a UPS between my computer and the live voltage. Figured maybe it was getting some dirty/noisy voltage. In doing this I forgot to plug the USB DVD drive back in. System booted up without any issues. After a few minutes I realized the DVD drive was off. As soon as I turned in on, Windows Vista 64 Ultimate hard locked. The next reboot resulted in the instant power off problem upon reaching the desktop. I can repeat this pattern 100%. I have tried BIOS versions 1.6 and 1.73B with my MSI K9A Platinum motherboard. I was also able to cause the hard lock issue using a USB Flash drive. I am hesitant to blame this problem solely on Vista or the motherboard. Considering the ReadyBoost feature, I'm sure extensive testing was done with USB devices. USB mice and keyboards do not cause any issues. I moved the DVD drive to the internal IDE port, and it hasn't crashed, locked, or shutoff since. I'm considering an RMA, but it works in XP. So can I really justify it?