GUI not working, after bootup, no video.

Archived from groups: microsoft.public.windowsxp.help_and_support (More info?)

I have WinXP Pro SP2 installed, McAfee Virus and Spam, AdawareSE and Spybot.
All are run weekly and MS updates automatically. I have 2 160GB SATA HDs
RAID1 (mirrored in the BIOS, Promise 20736 on MSI-6570 MB).

Everything has been running fine for some time (since SP2 was released), I
was not installing any software that I'm aware of.

MY GUI STOPPED FUNCTIONING! The computer boots up and seems to be working
fine without video (startup sounds, PDA connection, etc.). I've tried Safe
Mode, same result. I tried installing WinXP on different HD, no other
changes, and everything works fine including video (not h/w monitor or video
card)!