most of the blue screens are irql_not_less_or_equal. Dumps usually show ntoskrnl.exe problems. Most of the time Safe Mode boots, normal boots are 50%. As indicated by the title, I have ran each, but after removal, the computer still does not boot successfully. The PC is 64 bit Vista. I can download files from another computer and use a USB drive. Incredibly frustrating situation, but I saw someone else on this board who had a similar problem solved within the last month, so I have faith. Please help.