My samsung is doing the exact same thing, after a few seconds of changing to another channel the sound suddenly turns off. Have you found out the problem and how to fix.
Several of my channels all of sudden have the sound cut out after about 4-5 seconds when switching to them. the picture is fine on all channels but 3 or 4 channels now lose sound after 4-5 seconds. Can't seem to find an incorrect setting? Just started having this problem.