mold

i'm running the 7057 build of x64 Win 7. i have the v103 win7codecs installed, and the v105 win7x64components. when i try to play avi files uisng Media Center, most of them work but for some of them the video works but i get no audio. there are no software errors displayed, but my Sharp LCD TV displays the following error: "An incompatible audio signal has been received. Check the output device settings." the TV is connected to the HTPC using HDMI. these same avi files play ok using vlc or graphstudio. any suggestions on what i need to tweak to fix this? thanks.