No sound through HDMI, but also cant mute

I just bought a Dell Studio XPS 1640. It has a blue ray player and HDMI out. I have a sony kdf-e42a10 tv, its older but has HDMI. My problem is that I cant get sound to play through HDMI. I have looked under the sound control panel and the HDMI out has a green check mark next to it. I have also tried disabling the other sound devices. The strange thing is when I go to play a blue ray movie using PowerDVD DX the sound comes out of the computer speakers but I have no control over volume or muting. It wont let me mute the sound or turn it up or down. I tried the controls on the case, the controls in PowerDVD DX, the volume control in the task bar, nothing worked.

Should I try a different program?

Any Ideas?

Jeremy

it is the program (powerDVD DX), Any one know a free program that plays blue ray?

Jeremy