Is there ANY pattern to when this happens? That would be a strong bit of information. Frinstance, if it happens every once in a while, but every time it's at the beginning of an ad, or at the moment when the program is supposed to resume after an ad, or when the studio breaks into live from the news desk for a news promo... in other words, when the actual audio track changes in some way, even including just being gone for a second... that would point to something.