5.1 music playback problem

When trying to playback a 5.1 music file the time counter runs very fast, once the conuter reaches as it sees it the end of the track the audio stops. This only seems to happen for content recorded in 5.1. Normal stereo albums play fine. Essentially if the track was 4 minutes it would play for just over 2 minutes. Other thing is it shows the stream as 2 channel but does playback correctly through all 5 channels.

I'm using a nightly build from 28-08-12 and I presume this is a bug in the new HD audio which I may add apart from this minor fault is outstanding.