I had a similar problem, the game would not launch, and I was certain it was because I had merely set aside a save and tried putting it back in. I thought I'd corrupted the game files somehow. Then I remembered I also made a slight change in the config file. Once I changed that back, it worked fine. And thankfully it did, because I was a fair ways into a video walkthrough I was doing, and would have had to restart the whole game otherwise!