Is this normal? When I play a DivX using MPlayer2 from the beginning, all 4 channels are synced. But if I change the volume, only the front 2 channels lower. The rear 2 do not. I thought it was a fluke in the DivX I made but when I played other ones, same thing. And I don't recall having this happen to me before. Does anyone know what could causing this and how to fix?