Have you set up what audio formats your TV can accept in your audio drivers? It might be getting audio streamed directly off of the DVD in a format it dislikes. If you can't find somewhere to set that, you could maybe install something like ac3filter and make adjustments there.
I was going to use your ac3filter suggestion last night, but the computer is now freaking on me. I was going to uninstall the VIA audio drivers and the nvidia drivers (why would anyone make you install two sets of drivers to control one function is beyond me) and the computer just started shutting off for no reason.
Now I am starting to think that after switching from an X2-4200 to the X2-7750 and changing the mobo that the power draw may be a bit much, but i only changed those two components, so I doubt it can seriously put that kind of a power drain on a 300W PSU (albeit the PSU did come with the case and the case is an nMedia 200B).
But I had no problems at all pushing sound through HDMI with the 690G board - I only didn't get sound using the TV-tuner. I may have to put the 780G board in there and see what happens.
I am not impressed with the GeForce 8200 though. I used the gigabyte version of that chipset in my sisters HTPC build, and she just mentioned that she had to iron out some problems, mostly work-arounds though, not actually solving the problem.
Well . . . . . .I see another swap session inmy future if I can't get this board stable - WITH sound - by the weekend.
. . . this is the digital projection of your mental self. . . .