Very sorry to hear about your speaker.
Does it always happen in the same place in the movie (like if you rewind, will it happen again)?
Since plugging in the optical cable, have you unplugged the analog cables? Any DTS-capable receiver will note in the manual that DTS soundtracks cause players to output noise from the analog outputs; some receivers have precautions to avoid the analog inputs from being used at all when the DTS decoder is in use. I couldn't tell you why this happens at all, but I never connect analog audio cables to an input on my receiver if I intend on using digital audio with that input.
I would suggest also reposting this in the Home Audio & Video forum. You'll get a different audience, and there are definitely folks over there who are quite knowledgeable with regard to this type of thing. Have you called Denon yet?
I have a PS3 with firmware 1.51, 60GB. I have the HDMI connected to a projector which has no sound capabilities. So I have connected a TOSlink cable from the PS3 to my Denon receiver. I have absolutely no problems with standard DVDs playing the soundtrack, whether it is Dolby Digital 5.1 or DTS 5.1.
When watching BluRay discs, the audio soundtrack will play perfectly fine thru the analog cables from the PS3 and through the TOSlink cable in PCM mode but I am limited to stereo output only.
When switching to bitstream mode and enabling 640mbps DD5.1 or DTS5.1 I will get true surround sound mode. But the soundtrack intermittently cuts out and is replaced by a loud static noise (like a "PSSSHHHHHT") or a shrieking whistling noise. The noise lasts from a split second but can last as long as several seconds and then the soundtrack reappears as if nothing happens. The noise is quite loud, louder than the soundtrack, loud enough where it blew a tweeter in my front speakers (a real bummer)
I have browsed some forums and this seems to have happened to some users but they were unable to resolve the issue. Some users reported that the issue also occurs in the audio from the HDMI connection as well.
Again, to clarify, this only happens with BluRay, not standard DVDs. I also noted that I do not have this problem with "Ice Age 2" but the issue is REALLY bad with "Superman Returns". The discs are definitely not smudged or dirty as I checked them all before inserting into the PS3.
Someone mentioned that older receivers may not handle the 640mbps signal, since DVDs were speced to a max of 192-448mbps audio signal(depending on format). Is this true?