Comment 4 for bug 844347

I am experiencing the same issue. I hopped onto the upstream irc channel and here are some snippets of the conversation:

<achiang> hello, mumble 1.2.3-2ubuntu2 is hanging for me on startup, i get stuck in the audio wizard. a quick strace shows that it's infinitely doing a sched_yield() call
<achiang> any further debugging i can do?
<pcgod> achiang: your audio device is probably in use
<pcgod> (which will cause it to hang when it tries to play the audio file in the audio wizard)

I used lsof to try and find any open files related to sound to kill them off. That didn't seem to work. After killing mumble and restarting, I tried to just skip the audio wizard completely and just connect to a server, which also hangs:

<achiang> and now mumble is hanging upon trying to connect to a server
<pcgod> achiang: which is the same problem... the default settings have an "on connect" sound and it enters the same infinite loop when it tries to play that