I bought the LG 60 Inch Plasma over the weekend and hooked up the old receiver along with my XBOX & Wii consoles. I am finding that the volume from the AV system is jumping up and down very often even though I am not changing channels or moving between different video inputs. When it is down, you cannot hear it. I am wondering if it is because the AV system is not HD capable. I checked all the connections and they are okay. Any guidance or feedback is greatly appreciated.