Computer issue

[ITH]

If for nothing else im sure there is someone on here smarter than me when it comes to computer and hooking things up. Got a very odd problem. For the past 2 weeks i have had my computer hooked up to my sony bravia 48 HD tv through the HDMI port in my Radeon HD 6870. well everything was working fine then one day i turned it on the audio stopped working, i had not installed anything new or updated anything so i tried reloading the drivers for my card still nothing, then i rolled them back to a previous build still no sound. Finally i unhooked it from my receiver and hooked it straight to the tv i got sound well i figured that was a fix.

Now it happened again i haven't installed anything new but i have lost sound through my TV. When i hook speakers up to the computer it works fine i tried swapping HDMI cables and ports on the tv but it still does nothing also rolled back the drivers but still nothing. If anyone has an ideas or can point me in a good direction i would really appreciate it or if you need any additional information i will be happy to provide. thanks