I have reported it, 5th time now, picture is fine, recorded HD shows / channels, even the new spiderman film we bought 2 weeks ago from the virgin store, the audio was the same, it's not all the time but 60 to 70% of the time.
Picture is fine, just HD channels have an issue. I do have the audio connected from the TV to a sound bar via optical cables, however I get the same issue when the sound bar is disconnected (tv speakers)