Have you checked your bios to make sure the 5750 is set as the primary card?

Ya know, Phoenix, I wonder if I'm beating a dead horse.  I guess I should start from scratch, like "Does the TV even support what I'm trying to do?"  My TV is a Toshiba 62HM196 DLP.  This TV's gotta be at least 10 years old.  My son's TV is the latest and greatest plasma 55" 3D.  It's quite possible that my TV doesn't allow me to do what I'm trying to do.  Bringing my PC physically up to my son's location will pretty much tell me if this is what's happening.  In the meantime, I'll research the web and find out if this TV is capable of doing what I want to do.

Again, I appreciate all your time and effort and will let you know how things turn out.

OK Phoenix - I think I figured out what was going on.  I took my PC, physically moved it to my son's room, and hooked all up.  Same issue as I was having at my location.  I can only assume that somehow the PCI-E slot (or something with the motherboard) is not allowing the HDMI audio to pass through to the audio portion of the video card (although the DVI-D port works fine).  The last thing I could try is to take my son's working PCI-E card and put into my computer, BUT I will not do this because of the possibility if my PCI-E slot damaging his working card.  I don't use my PC for any heavy duty applications, so I'm just going to pick up an AM2 cheapo motherboard and go from there.  I'll update you on what happens when the new board arrives.

I should say I have never connected simultaneously to hdmi and dvi.  I am using ATI 5870 over HDMI to a flat panel. To get hdmo audio I am using these drivers:

Catalyst (13.1 WHQL right now) with (1) AMD HDMI audio driver, (2) Realtek HD Audio driver, and (3) Realtek ATI HDMI driver. Then you switch to hdmi output from Control Panel>Sound>1 AMD HDMI Audio Device>Set default.

ruber,

The ATI 5750 has two Bus' - one with a DVI for the monitor and a separate BUS for eiither DVI, HDMI, or VGA.  I do not believe you can use more than one device concurrently in the 2nd BUS.

I'll go ahead and use the drivers you listed.

Thank you.

Phoenix,

This is what I found out.  You were correct when you said a PCI-E slot rarely goes bad.  I installed a new MB (ASRock 4785GM-LE) and had the same problem.  Man, this was getting frustrating.  The solution to the problem was I had to install a fresh copy of Windows 7.  When I first put the MB in, I thought I got lucky not having to reinstall all my applications.  But after the problem did not go away, the last resort was to install a clean copy of the OS and take it from there.  If that didn't work, then I was at a loss.  Lo and behold, the fresh copy of Windows 7 and the video card installation did the trick.  Everything works as I wanted it, and I'm glad it's over.  I'm sure my old MB and PCI-E slot are fine, but I really don't care.  It works, and if it ain't broke, don't fix it.  I can only assume something in the OS didn't like something, and a clean install took care of it.  Consider it a learning lesson, I guess.

Again, thank you for your time in troubleshooting this issue.