I have a broad suggestion for anyone experiencing Blu-ray playback issues, whether they be from .m2ts or straight from disc: FORMAT AND START OVER!
Let me explain a little more...
I built my HTPC back in March. I immediately threw onto it everything that I had on my desktop computer (Nero, Photoshop, video editing programs). I also initially installed a codec pack (Community Codec Pack, I believe). I later added Lite-On Blu-ray drive and installed PowerDVD 7 and later 8.
I had the most frustrating, inexplicable, and sporadic issues related to lack of video or audio when trying to play .m2ts files in either PowerDVD or MPC. Sometimes the audio would work in MPC and not in PowerDVD. Sometimes I wouldn't get video in MPC. I tried uninstalling the codec pack and installed Vista Codec Pack instead. It fixed some of my problems, but I still had random issues ALL the time. Most of the blu-ray discs I tried would not play in PowerDVD without my going through AnyDVD and ripping out the individual streams. Just as many of you have, I tried uninstalling every last video program and reinstalling. I did several clean installs of PowerDVD, trying different releases, but I could never get consistent playback.
Like many others in this forum have, I considered giving up, as I didn't see all the hours of frustration as being worth it (seeing as how cheap standalone BD players have gotten).
At the advice of a post in this forum, I ended up trying once more with a *fresh* install of Vista. All I installed was Media Player Classic Home Cinema, PowerDVD, Haali, and AC3 filter. I also followed the excellent instructions here to get MPC-HC to use DXVA. (Just realized that I can't post links yet... ranpha.wordpress.com/page-1/
is the site.)
I can't even explain how well my system runs right now. It is like night and day. Every single BD disc and .m2ts stream I've played has worked flawlessly. I'm sure you've all heard it before, but I can't stress enough how many unseen and unfixable problems those GD codec packs cause. They even affect programs that bring and use their own filters (e.g., PowerDVD).
I have tried to install the ABSOLUTE bare minimum on my HTPC, and I leave Photoshop and all my other editing programs to my desktop (where they belong). Also backed up with Acronis when I got everything running perfectly. I haven't even needed to install ffdshow as MPC-HC and its internal codecs have played everything I've thrown at it so far. I don't use Media Center for anything but TV anymore. MyMovies looks nice, but I haven't really found it necessary since I use a mouse with my HTPC. I just added a link to my movies folder to the taskbar so it pops up with a menu (w/ folders for DVD, HD, TV, etc.). I like the consistency of playback in MPC-HC anyway (you can also set it up to control it with the number portion of you VMC remote).
I'm starting to ramble...but my moral of the story is that, when it comes to HTPCs, the simpler, the better, and avoid codec packs like the plague.
PS -- I'm running a 4670 and have had everything working well since the 8.9 drivers (currently running 8.11).