STOP error: cannot load winsrv (admin password)

When I recently installed the new Service Pak from Microsoft, I rebooted and got the blue screen of death. The Stop error said that it cannot load the winsrv file. I loaded the XP CD and tried to do a repair on the c: drive. My problem is that when I selected the drive to be repaired, it asks me for an Administrator password. Anybody have any idea what password they may be talking about. It is a new Dell (2.4 Gb processor). Any helo is greatly appreciated.