OK, totally frustrating problem. I've been using an old server box with an ATI Radeon 9700 pro video card (dvi to hdmi adapter) and an Audigy 2 soundcard to my Philips LCD for video content. Runs OK, but slow as hell.
I built two different boxes to replace this one (it's 2 feet tall and purple, don't ask...) but run into the same problem with both of them. I have sound coming off of the audio out on my new soundcard, but the TV won't accept it. If I flip the audio to a different input on the tv, it comes through fine. Just doesn't want to have both at the same time. One box has Intel integrated audio and sound, the other has integrated sound and a Geforce video card.
Any thoughts on why the tv fails to allow sound on the hdmi channel with the new setups?
Note: I've tried these systems with XP Pro and Vista both with no success.