Hmm maybe you try to download a fresh copy of the install files and try reinstalling it again? I think that would be the simplest thing to try first.
I did a google search and came up with this:
http://thevistaforums.com/lofiversion/index.php/t38676.html
Try using the tool they had recommended in there (Note: I havent tried / encountered it myself so i cant really help you much either)