MKV 720 AC3 5.1 freeze (CCoreAudioUnit::Close)

Hello all,

I'm having problems when trying to play some mkv files on my aTV2 (iOS 5.0.1 version 4.4.4) running XBMC Frodo 12.0-1.
I can correctly play most of them, but others output these error in the xbmc.log:
ERROR: CCoreAudioUnit::Close: Unable to disconnect AudioUnit. Error = -10860
WARNING: CDVDMessageQueue(audio)::Get - asked for new data packet, with nothing available

This is the complete log:
http://pastebin.com/MFpYvMbL

Any idea?

Thank you very much!