My receiver seems to be really screwed up. I have no audio coming through the surround speakers. On the front of the unit there are lights for the speakers and only the L and R lights are lit up even though no audio comes through those speakers, mainly only through the center speaker. When I cycle through the speakers with the A/B/C/D/E button all the speakers say 0db except the two rear ones, those have - -. I've tried resetting it to the factory default but that didn't seem to fix anything. Any ideas what's going on with this thing?