Comment 6 for bug 715099

The problem here it seems is that for some reason my pulse context or the sink info pointer is null. What is really odd here is that this piece of code has not been touched for a year. I'm not sure if its a pulse problem or the sound service. I have had a few of these crashes reported recently so it is something consistent. Have you experienced pulse dying on you at any point.

If pulse dies you should see the icon on the panel go to audio-output-none-symbolic. But of course on a normal system pulse would automatically respawn resulting in you not being able to catch the icon on the screen.

Either way this code should be rock solid in Natty (code base was refactored heavily between release 0.5.7 and tomorrows 0.5.9).

Any chance you could follow these instructions to turn off autospawn on your system.
https://wiki.ubuntu.com/PulseAudio/Log

The drawback of this is that you will need to start pulse manually after starting up and it won't restart if it goes down but at least we will know its unstable and from there try to collect some debug info.