You could try and run SFC/Scannow system file checker, it checks the entire windows system for missing files and attempts to replace them, if you go to this link, it will show you how to run it.
http://www.sevenforums.com/tutorials/1538-sfc-scannow-command-system-file-checker.html
VicI have 'Real Alternative' on my system, enables you to play 'Real' stuff without all the crap, I think I got it fromwww.free-codecs.comIt's about a 4mb downloadDave