0x7B indicates a boot sector virus (doubt it), or hardware misconfiguration/device driver problems (possible if you had CD access problems lately), amongst other things (not very helpful), according to the MS site. Although if you can't even boot into safe mode, only thing that's left is a reinstall At least try repair reinstall first though, though that'd downgrade the system to either Gold or SP1 status, then reapply patches as needed.