Going out on a limb here, but try installing the K-Lite Codec Pack and select Windows Media Player as the default.
Download K-Lite Codec Pack 5.40 (Full) - FileHippo.com
Can't hurt and they're always useful for audio and video playback.
Also, go to Control Panel > Device Manager and look for any entries with a yellow flag.
No go to Start > Run, and type services.msc, scroll down to the Windows Media Center entries and make sure all are started.
Also, do you have the latest version of VLC.....1.03?