I have a JVC RX-6042S receiver. When I put it in "DVD" mode and turn the volume up, I get a message of "Overload" and I have to turn it off. In this mode all of my speakers are working including the sub wfr. When I put it in "DVD Multi" mode and turn up the volume, it will play as loud as I want it to, except the rear surround speakers and the sub wfr are not activated. I bought new wires and I still receive the same problem. What is making the amp/receiver overload and how can I fix it?