I have the same problem, however this is a new build, with an intel extreme 6850 cpu,asus striker extreme mobo, using windows vista 64 ultimate.
Everything loaded in nicely, I was in windows beginning to load the mobo drivers, gpu drivers, etc. It asked for a system restart, so I said yes, what did not realize is that windows was downloading it's updates, so before the system could reboot it had to download those , 47 of them to be exact, once it was done the system rebooted, went to a black screen with a cursor blinking in the top left corner, I figured it was still working, but half an hr went by and still nothing. SO I shut down the system and restarted it, everything seemed to be booting up nicely until it went to a black screen and said
disk boot failure, insert system disk and press enter. I installed vista disk in my cd drive, and it would not read any of the drives. Starting to think windows vista has issues.