Thanks for your reply guys. I know the format does change with a commercial, but most of the time the sound lost is durning the station program. The HD channels are the only ones that lose sound, and AvFan is right about CBS, it's the worst of them all. I'll check with my cable provider about the signal strength. I will also switch over to component vice HDMI and coax vice digital audio. Thanks again guys, I'll let you know something in a few days...