Z-5500 5.1 and Blu-Ray Dolby digital playback question

[Showtime]

I recently purchased the Z-5500 5.1 speakers along with a new Dell XPS-410 system with Blu-Ray, so far the experience has been mostly fantastic (even though I have only had the pleasure to watch a few Blu-Ray movies at this point). The Z-5500's have performed flawlessly so far...except for one little (well really BIG...though I am about 99.9% sure it is actually a Sony DRM thing Grrrrr!) issue. But anyway, I am running a Dell XPS-410 with Vista, Windows Media Center/Cyberlink PowerDVD for Blu-Ray playback using a Creative XtremeMusic soundcard connecting to the Z-5500 5.1 speakers using the toslink digital optical cable. With this configuration I am able to playback all forms of sound with no problem from Music Cd's, DVD Audio discs, DVD standard movie discs, MPG music stored on my hard drive, internet radio all of these play perfectly over the Optical input and all play in the appropriate modes as needed (IE: Dolby PLII music for regular Music (CD, MPG, Internet radio...Dolby Digital 5.1, DTS surround for DVD movies and DVD Audio discs) The only problem I run into is with the Blu-Ray discs...When I play the Blu-Ray they will only play in the Dolby PLII mode...now the Cyberlink PowerDVD has a option setting that lets you change the speaker setup and one of the options is SPDIF (normal option is 2.0 channel with stereo/Dolby 5.1 (but this option does not allow Blu-Ray to play in Dolby digital 5.1 only Dolby PLII movie mode). Now if I select the SPDIF option in PowerDVD and restart the Blu-ray movie it now starts in Dolby Digital 5.1 as indicated and confirmed by the Z-5500 control center and it will play all the way through the opening Blu-Ray promos and the previews for the movies coming to Blu-Ray with perfect Dolby Digital 5.1 sound (and….at least on the new James Bond Casino Royale movie the animated menu music and sound effects play in perfect Dolby Digital 5.1 also and it all sounds Great! But then when you actually start the movie and the movie begins......SILENCE...zip...nada...not a peep, so I guess my question in search of an answer is, is this an issue with playing Sony Blu-Ray on a PC while using the Toslink Digital connection and the SPDIF PowerDVD option where SONY just does not want me to be able to fully enjoy their product on my very expensive PC/Home Theater setup with the best possible sound by using DRM to piss on my Dolby Digital 5.1 Blu-Ray parade????....or am I missing something here? Thanks in advance to anyone who is brave enough to wade through this and possibly provide me with any information on this issue.