[Codeknight]

I get this same problem now. my friend got this problem too before we mixed up the disks (his computer at his alive). So I'm pretty sure that the problem is the computer is unable to read a specific file on the disk resulting in a corrupted installation. If this is the case there are two ways I can think of to fix it:
1. Buy a new disk
2. Borrow the disk from someone and copy it. (This shouldn't be illigal because you already bought the game, as long as you don't hand out copies to other people)