1) Is this on Steam?
2) If on Steam, did you VERIFY the local content?
3) Do you have any MODS?
It sounds like part of the game was on the drive you wiped.
Yes, its on Steam.
Yes, I verified the local content (and also reinstalled the game).
No, I don't have mods
And the game was installed on driver D, just Steam was installed in the C and all my other games from Steam that are in the same folder with New Vegas in driver D are running, but I always have the problem to run them with error 53, so I have to launch Steam offline mode but that doesnt help it either with Fallout