Frodo RC1 Ripped Bluray Problems

Hi there,

I'm a new user trying to get XBMC set up, and I'm having trouble getting ripped Blu Ray files (the BDMV and Certificate folders) to play. The menu opens up fine, but when I try to play the actual movie, there's no sound and the video stutters at an unwatchably slow rate.

Here's my setup:

Windows 7 Home Premium x64
Radeon HD 4600
HDMI running from Radeon --> Oknyo Receiver --> TV
Latest Radeon Drivers Updated
No Realtek drivers installed
Tried several different video settings in XBMC and haven't found one that works (DXVA vs. software rendering, sync playback to display)
Audio set to 5.1 HDMI with WASAPI selected

I'm able to play other media types just fine. And it's strange that the Bluray menus work perfectly too, no?

Any ideas?

Thanks so much!