I have run FIXBOOT, FIXMBR, and chkdsk /r, but the computer still just reboots. It comes up with the following screen to select:
Safe Mode with Networking
Safe Mode with Command Prompt
Last Known Good Configuration
Start Windows Normally
No matter what I select, it just reboots again.
I have run anti-malware scans until I can't see straight, using the latest copies of AVG, AdAware, Spybot and Malwarebytes' Anti-Malware, but still it keeps rebooting.
This computer was working fine a few days ago. A few weeks ago I tested the power supply, and it was fine.