Thanks for the response. I have a few more steps to try, if you would like:
1. Go into Device Manager. Expand the Display adapter and Sound, video and game controller sections. Take note of what devices exist under both categories.
2. Right-click on your Sound and Graphics driver, and select uninstall.
3. Restart the computer. This will force the drivers to be reinstalled. Then go into Device Manager and take note of whether or not there are any differences.
Try establishing sound through your HDMI connection now and see what happens. Keep me posted!
Mario