One other route to try: I'm having no problems with 5.1.889 and Power DVD 7. A few months ago I had to replace my DVD drive, and the new one came bundled with an installation CD for v. 8, but that turned out to be an OEM version which lacked some components (I forget what) essential to viewing commercial DVD videos. So I restored my HD to the previous day, to get ver. 7 back, and it was fine again.
So see if you can find somewhere (Cyberlink, maybe?) a copy of Power DVD 7 and try that. To the best of my memory, the only significant change in v. 8 vs 7 was the ability to add other skins to the default one.