I assume you have tried rebooting your pc?
Failing that, its hard to say without knowing which particular patch caused the problem. I would suggest removing anything from the root folder that you have placed there. Delete any .big or .xml file to get the game back to its original state. If the game now runs, install a patch at a time and re-run the game. That way you'll identify the problem.
If it still persists, try searching on the forum for the thread from the creator of the patch and see if anyone else has had the same. Hopefully the patch maker will be able to help.