I have an 47PFL7422D/37 with a HDMI DVR cable box, Xbox 360 (via HDMI) and a PS3 (via HDMI) The problem I am having is that when all three HDMI are plugged, sometimes the sound will go out. The only remedy is I unplug everything and switch inputs. I am using HDMI 1.3a cables that I purchased from monoprice. Any ideas?