Very odd. I have the same gear as you, and the only time that I have had something sound like what you say, is when I am in the wrong audio processing mode, such as 5 speaker "3D" or some simulated surround like DTS:Neo6 or ProLogicII instead of making sure that the source is playing 5.1 and my receiver is matched. Actually, now that I think about it, as long as the DVD player is NOT set to 2 channel audio output, the receiver autoswitches to the correct audio (as would pretty much all receivers), but I popped in the first Harry Potter movie this past weekend, and the sound was a lot like you said. Unfortunately, I couldn't find anywhere on the disk to change from 2 channel to 5.1... Very strange. I never did check the DVD box to make sure that it even had a 5.1 track on it. You would sure think so, but I got the first 4 movies as a "box set" which seemed to be a mix of "2 disc special editions" and some regular single disc editions depending on the movie.
Anyway, it is at those times when a movie doesn't default to a 5.1 sound track that I notice what you are saying. Some worse than others.
Let us know how your testing comes out.
