I have a Magnavox 37MF337B 37 inch TV and a Pioneer VSX515 Home Theater receiver. The TV is connected to the receiver using a digital coax SPDIF cable. The the problem I'm having is when I watch a digital channel over broadcast or cable, the audio frequently cuts out. When watching any analog source, there is no problem at all with the audio. When I watch TV using the speakers attached to the TV, there is also no audio problem on digital or analog channels, only when I listen to audio from digital TV stations through the receiver. I've tried 2 different digital audio cables and the problem persists. It happens on all digital channels on cable or off air. Anyone have any idea what could be causing this?