Windows 7 powerdvd no sound

Hello everyone, new guy here. I built a new (nothing fancy) rig within the last six months and have a very odd problem that I have been unable to solve.

Out of all the hardware parts, the rig includes a Gigabyte GA-EP45-UD3P with GeForce GTX260, spin point tera-byte, dvd burner and a blueray rom. I am using HDMI connection which goes to my 1080p 46 inch LCD Vizio.

Here is the problem, when my Windows 7 (beta) logs-in, I hear the Windows log-in sound through the HDMI cable to my TV and it's speakers. If I use DVD shrink or firefox to play a video, it plays the audio with no problem.

However, there are some applications which will not play sound. I can see video, but no sound. If I use PowerDVD to play same movie as I did using DVD Shrink, I hear no sound. If I use Arcsoft media to play from my Blueray drive, it doesn't play sound either. Are these 'higher-end' applications using a different decoder that I don't have?

What am I missing? Is there some specific setting that I didn't turn on via Bios or Software? I have been battling this for more than six months and cannot figure it out. Help! Please!!