Ever since I installed the new Windows 7 upgrade, my laptop speakers won't play a thing, ever. Yet if I plug headphones in, I get sound coming out of the headphones. Also, whenever I try and play anything in Windows Media Player, it comes up with a message saying "Windows Media Player encountered a problem while playing the file." If I click on the web help link, it gives a code "Windows Media Player C00D11B1 Windows Media Player can't play the file." If anyone can help suggest how to fix these problems that would be much appreciated, thanks.