Comment # 13 on bug 999738 from Dr. Werner Fink

OK found the reason.  For a better support I had switched pulseaudio from user
based configuration to a system wide configuration.  The reason for this change
is to have a better audio support for several open X sessions on vt7, vt8, and
vt9 at the same time and also supporting hibernation.

This change had caused trouble with KDE plasmashell due to a missconfigured
system mode of pulseaudio which is now fixed.