Windows Media Player Problems.?

It's been like this for quite a while, but now it's starting to bother me. Every time I try to play a MP3 file or MP4 or even AVI File, it says "Server Execution failed". What can I do to fix this. And I have Windows 7 Home Premium and I can installed with my HP laptop. As a matter of fact, I can't play anything with WMP now, I can't even open it!