Get your windows cd and use the repair option.
Every time I try to start up my computer I get the following message:
"Windows could not start because the following file is missing or corrupt: windows/system32/config/system
You can attempt to repair the this file by starting Windows Setup using the original Setup CD-ROM.
Select R at the first screen to start repair"
The problem is that the computer reboots but doesn't start the Windows Setup. Is there some menu you're supposed to go to or something else?