Do you currently have any mods in your override or anywhere else in your SW KotOR II directory?
If you do, then uninstall/delete all of them. Then untinstall the game. (feel free to keep your saved games if you have any) then reinstall according to the SECOND POST of this thread:
If you don't have any mods, still uninstall and reinstall according to the SECOND POST in the link above. You dont have anything to lose, really. If that doesn't work, then double check if your drivers are truly updated to the current version.
Are you running the game on a desktop or a labtop?