I was just making sure you had done the menu thing... seems so obvious until someone doesn't actually do it, then you wonder why you didn't ask them to do that first.
DEFINITELY: Call your cable company and find out what other boxes, digital or HD that they have. I am only using a digital connection between my HD/DVR box and my receiver. No audio problems on anything.
Who is your cable provider and what type of cable box do you have? Others may have even more info to give than I do, but I would expect that the cable company can be put on the line for a better product for you.