So this is happening at specific passages on specific discs? It sounds like there may be more going on here than just the 1050's normal safeties. I couple of things that I might try just for curiosity's sake would be to try playing those passages using the analog audio outputs from the DVD player instead of the digital, trying the passages with the sound muted entirely, or (if possible) even trying a different DVD player. Also, I'd double check all my speaker wiring (might even try disconnecting the speakers and playing the passages) to make sure there's not a wiring mistake there.