Comment 3 for bug 559545

Jamie, the reason I suspected apparmor was twofold. First I grepped
for dev/shm in /etc, found some likely looking files in
/etc/apparmor.d and then set about purging apparmor to see if it was
the problem.

The results I saw (from fgrep dev/shm -r .) contained:

  ./apparmor.d/abstractions/audio:/dev/shm/ r,
  ./apparmor.d/abstractions/audio:owner /dev/shm/pulse-shm* rwk,
  ./apparmor.d/abstractions/libvirt-qemu: /dev/shm/ r,
  ./apparmor.d/abstractions/libvirt-qemu: /dev/shm/pulse-shm* r,
  ./apparmor.d/abstractions/libvirt-qemu: /dev/shm/pulse-shm* rwk,

Secondly, after removing apparmor and rebooting, the problem went
away.

However, while writing this message and repeating the grep in a backup
I realise / remember that I did also remove some qemu and libvirt
packages at the same time, as well as virtualbox; I don't run any VMs
at the moment. Your question about libvirt has struck a chord.

(Also, wrt virtualbox, I remember following some instructions from
Jono Bacon's blog - iirc - maybe 6-12 months back. ISTR that involved
adding a PPA; could that have been yours?)

I don't know what more information I can add to this bug now. It
sounds like it could be invalid, but I'm happy to help reproduce if
it's still of interest.