>I was just siting here working when suddenly my PC rebooted. Now, after I start up, and while it's still sitting at the login screen, the Blue Screen of Death flashes and the PC reboots..It all happens very quickly wih no time to do anything. I can reboot in Safe Mode, but what do I do now?

To determine whether it is hardware or WIndows / software: reboot and press the key to load the bios settings. Dont change anything but just leave it there and see if it reboots as well after a while. If not, then you know its not hardware but something in Windows. In that case, reboot into safe mode and see if it still happens.