And, just to confirm, you are not using a cracked version, right? (Even if legally purchased, using any "no DVD" crack counts)
The devs have admitted that the game uses a 'FADE'-like protection, where various parts of the game break in bizarre ways intentionally when not using the original files.
To be fair, never heard of this one, but it's something to consider. (Otherwise, as others have said, sounds like a borked install)
__________________
|