I've found several threads that explained exactly the same symptoms that my PC was having:
Intermittent crashes to a black screen and a message that the video cable was not connect. After several reboots discovering the BIOS will not load and is corrupted. Removal of BIOS battery and clearing the BIOS to get Windows XP to load up again. Then another crash. I started reading the forums hear and notice one post talking about a motherboard shorting out with the PC box.
After thoroughly inspecting my machine and while doing so I was touching a good metal area of my box when trying to boot up my machine -- yeee ouch! I got zapped with some low voltage and the cause was finally revealed! I traced every connection and then the wires and low and behold my CD ROM music power cable (small gray wire) was pinched in it's drive bay against the metal! It had been partially severed so I chunked the entire wire altogether just in case the small wires where massed inside!
My problem was solved. I hope this helps because it took me several weeks to figure it out.
Since the BIOS got corrupted to hell and back, it encouraged me to read the mobo's owner's manual and upgrade my BIOS to the latest version -- actually quite simple using the CD that came with the board.
