Ok, whereas I will admit that it may appear to be a weak answer, funnily enough it tends to fix problems. If not, you would need to provide more information:
start off with the following:

did it work at first?
what has changed to the system before the error started appearing (hardware added, software added)?
what is the exact error message (if any)? Is it always the same error message?

And, if you are worrying about this: the Uninstall I did couldn't delete the saved games, so if you reinstall to the same directory you have it in now, your saved games should be safe.

Hope this helps...