Yeah delete the folder the game extracts into completely. That way anything hidden will be deleted. Do a fresh install with the game. Just in case the original download became corrupted. You should download the game fresh. To eliminate path issues it is always a good idea to create a new dedicated folder for any game that you will have regular updates with. Like on your main hard drive create a folder named HHG, or something similar. When the game goes to extract direct it to that folder. This should clear up any issues with your saves. I have had similar issues before with other games, and most often it was a path issue where it crossed with an earlier version.