Just built a HTPC with a DG45FC (IDT audio and X4500HD on board) and have it hooked up to my Samsung LN52A650 LCD TV over HDMI. When in Windows XP most brief sounds (Windows warning sounds and browser click sounds etc) do not get picked up by the tv. Occasionally a brief sound might get picked up but then will sound nothing like it is supposed to, it will be distorted.
Now, when I go and click on an MP3 or other continuous audio stream then it will get picked up by the TV and sound fine. I've tried driver reinstallation, playing with the audio settings on the computer, updating TV firmware and motherboard BIOS to no avail. Anyone have any ideas?