I have had this problem since UP5 was installed on my system. I am using Cinnamon on a 64bit LMDE install.
On occasion XBMC will lose all audio output and have jerky video output. This only occurs when selecting something new to play (never in the middle of something) and with no clear pattern of failure, sometimes I can watch 5 things in a row, and other times it will fail straight away.
I have discovered that whenever this failure occurs, there are 2 xbmc processes in system monitor. One process seems to be doing nothing and taking up less cpu & RAM than the other. If I kill the phantom xbmc process (while keeping the program running), then sound will resume working as normal.
A less frequent issue I have had in XBMC is where audio starts playing through my HDMI connection rather than my PCI audio card. The HDMI sound is disabled in the system sound program, and the PCI card is selected as default for both the OS and XBMC. There is no phantom process when this occurs, and all I can do is reboot the machine.
I have had no issues with any other audio using applications.
My PCI card is an m-audio Delta 44, which has not worked well with pulse audio in the past, but it was fine with LMDE until UP5. I would rather not uninstall pulse, but if there are no other solutions, then i will do so. I would like to get this fixed as XBMC is pretty much the main use for this machine, and the workarounds I have are not ideal.
Any tips are appreciated.