my computer uses my HD tV as a screen (with a HDMI cable, connected on my 6800). I never had any graphic or sound problem (for about 4 years), but today, I updated my driver, and no more sound !!
I tried to change the cable, but no more success. I uninstalled and re-installed the driver too...
of course, I checked that my problem doesn't come from tv : I connected my Game console on it, and no problem. I check TV's config too.
Windows (7, 64 bits) tells me that everything works perfectly.
I think this update version has a problem, but I would like support answer, and if I can find somewhere an older version of the driver (to confirme that it is a driver problem).