Media Center sound not working

My Windows Media Center has lost its sound. I get picture, but not a peep from the sound. All other applications that have sound are working fine, so I know it's not the sound card. I contacted the computer manufacturer (HP) (their on-line chat assistant). HP had me run Media Center setup—no help. Then they sent me to a site to get a new codec. That did not help either.

Suggestions?

Check to see how your audio device is configured
Right click the Speaker in the tray next to the clock, then select playback devices. Highlight the device with the green check mark. Then click configure. If it is not configured for 2 Channel, try setting it for 2 Channel and try Media Center. I have been having this problem and this makes Media center work although everything else only plays in 2 CH.