I'm having a problem with the sound through my system. I have a Sony STR-DE635 receiver/amp and a Panasonic DVD-S35 DVD player. They are hooked up using an S-Video cable and a digital optical cable for the audio. Nothing fancy . The problem is, since I replaced my sony player with this one, while I'm watching a disc in Dolby 5.1, the sound will often get quiet, about half the volume It's at, and then slowly come back to the original volume over a few seconds. It does this repeatedly during movies, and always in the same spot in the scenes. It does not happen when I turn off the digital sound (I don' t have DTS so I can't test that0. I've played with the audio options on my player and nothing has helped. Any suggestions?