Windows 7 - MC not playing DVDs Properly (sound issue)

I have a problem with my Windows 7 Media Center. When I try playing a DVD on it (does for only some DVDs), it plays the background music and the video, just the voices are gone. I made sure it wasn't just the movie by enabling closed captioning and using a regular DVD player. On the regular DVD player, it ran with everything voices and all. Anyone know what could be wrong? I do have Home Premium so it shouldn't be the codecs I'd guess, but I'm new to this stuff.

What speakers are you using? ie. stereo/2.1/5.1 etc.
It sounds like you have more channels enabled than you have speakers!
If you don't already have it installed, go to the Asus Support site for your board and download the audio driver and utilities. The board has auto jack sensing, so you may be able to just unplug your speakers and then plug them back in again to have the board auto adjust the sound settings, if not, load the sound manage application, which I think will be Soundmax, and adjust the audio output to match the speaker configuration that you have

Could be a problem with audio codecs - have you tried playing the DVD in another program such as VLC?

-Bill