Purchased 705 two weeks ago. Have a directv dvr and a dvd player running to it through hdmi cables. Have Polk Monitor 50s and it has sounded amazing until yesterday. The volume goes up and down on its own. The volume is not changing on the receiver display. The volume basically goes from normal to mute to normal.....non stop. I switched around all the cables and still have the problem. The strange part is that the dvd player still works fine going through the receiver. If I plug the directv directly into the tv the sound works fine. Is one of the hdmi inputs on the receiver bad? Any help is appreciated.