Saturday night I was working on my desktop PC and was attempting to kill a program. I hit CTRL+ALT+DEL, the screen changed to VGA and the task manager came up. I killed the app, opened a cmd window and manually ran shutdown (shutdown -f -r -t 0). That hung so I hit the rest button. Not preferred, but has never caused a failure for me. The computer boots up to the loading animation and shuts off. So I got into recovery (Win 7) and had it check the boot process for errors. None found. I reboot the machine with the DVD in the drive. It gets to the same place (Windows animation) while reading the disc and the computer shuts down. So I grab Ubuntu Live 9.10 and am able to see all of the partitions and data. Ubuntu also does not detect any disc errors. I had Ubuntu detect that my laptop HDD was failing a week before it died, so I trust it. Seagate Tools doesn't find any problems either. A friend thought that it was the PSU, but that can't be possible given that I can boot with the Live cd. I've pulled all but my video card (mobo has video on board) and my other optical drive. I built the computer (5th or 6th PC I've built from scratch) and have worked in both PC hardware and PC software support since the early 90s. So I'm not a n00b. Frankly, I'm baffled. Anyone have any ideas?