Hi.
Do not run steam myself, but just googled your fault and every response so far has been it is a steam fault not a game fault.
First try a reg cleaner. CCleaner is free and really good. Download from reputable site of course.
Final action I guess would be to reinstall steam. Unless someone else can come to your help, that is all I can offer.
Hope the reg cleaner works. Would stop a lot of messing about.