I have a Sony receiver and once in a while it will go into a "protected" mode (the display says so) and I will lose all the sound while playing DVDs - especially Sci-Fi with a lot of sound effects. I noticed it happens more frequently when I have the volume pumpped up and/or when the "base boost" and "equalizer" feature were turned on. I fiddled with the equalizer adjustments and it did not help. It seems turning down the volume is the only way to reduce the sound been shut off. And I am talking about way low on the volume like 1-2 notch above the mute. Help!