This has happen twice, once a few months ago and then again last night. I turn to, in this case my local Fox station, I do not recall which channel I turned to the first time it happen, and in the back ground of the audio is an annoying whistling sound that is constant. It stayed if I turned the receiver off and back on, switched channels, and I even tried replacing my HDMI cabling to the television. The receiver is connected directly to the tv. The only thing that stopped it was a reboot. Anyone ever have this happen or have an idea of what might be the cause? The tv is a 3 year old Sony and with a recent SW update so I am wondering if that has anything to do with it.