I have a VIP612 and tonight the screen when black and it started making a "whooping" siren/alarm sound. It was strange. The picture was black but the audio was coming through. I had to unplug it to reset it and get it to start working again. It did this a few weeks ago and thought it was a fluke, but after happening again it appears to be something the receiver was designed to do. I just don't know what it signifies. Has anyone else seen this behavior?