Yes, and I know it sounds like a strange suggestion, but I have seen relative issues like this before. If you have no customized your own background, however, it's very unlikely the stock background theme would be the cause.
In regards to sound, depending on how your PS3 and Receiver are configured, this may be the issue. To answer the above question, the Walking Dead does nout output in 5.1 or 7.1(2). It is a stereo only title. If your system is attempting to force stereo sound, it could be affecting the game. Try connecting directly to your tv, using its stereo speakers, and see if the problem goes away.