Sometimes it seems like Windows just builds up little bits of information it has misplaced, like the correct dll for your file. In order to fix it you can try the windows repair tool that takes some special skill or try a program more like PC Health Boost . It helps by doing a lot of the hard work for you.
That program can be found at http://www.pchealthboost.com/blog/ my original link didn't seem to work.
Figured out how to make the link for you, sorry for the hold up.