Help with 3d HSBS MKVs containing HD Audio

I re purposed one of my gaming machines as an HTPC and am having issues playing back 1080p 3D HSBS MKVs that contain HD Audio tracks in XBMC. The videos play, but playback is sporadic, and the audio cuts in and out. CPU/RAM usage never go above 15%. HSBS 3DMKVs with standard DTS/Dolby Digital play fine, as do standard 1080p rips with HD Audio. The files are ripped directly from my Blu Ray collection and stored locally on the machine. They are anywhere from 15-50 GB in size. Here is more info on my setup. Any help would be greatly appreciated.

Core i7 920
Nvidia GTX560 connected to Denon1909 Receiver (Setup using WASPI Audio via HDMI)
6GB Ram
Windows 8 Pro
XBMC Frodo /w Aeon NOX Skin

Thanks