Comment 26 for bug 221038

It means the pulseaudio daemon has frozen and is not responding to the normal terminate signal. So you have to brutally kill it with the KILL signal instead (kill -9). That is why the two first kill commands do not work.

I've now disabled pulseaudio on all of my different Ubuntu 8.10 installations, I cannot use it, I find it unacceptable with crashes and freezes, especially when it does not add significant value and ALSA by itself works fine. In case anyone else has problems with pulseaudio crashing and want to use pure ALSA until fixes for these problems appear in updates, I documented what I did to disable it here:
http://folk.uio.no/oyvinst/disable_pulseaudio.txt