Google reveals that lots of users are having this trouble; many of them relate it to sound access.
Well, I think I pinned it down to an ALSA problem.
Strangely sending a SIGSTOP and SIGCONT recovers it briefly. Hope fully I submitted enough debugging for it to be fixed now.
Apart from the above bug, I do wish Ubuntu would do ASLA device sharing out of the box and configure everything to use ALSA, and do ESD sharing out of the box and configure everything else to use ESD, and ESD to use ALSA.
Here is my config to do that:
/etc/asound.conf - this lets multiple ALSA clients use the audio device at once
# Example /etc/asound.conf or ~/.asoundrc file showing how
# to configure ALSA so that a dmix plugin is used by default
# The writing of alsa-lib configuration files is explained in
# /usr/share/doc/libasound2-doc/html/index.html, provided by the
# libasound2-doc package.
# Make ALSA apps default to using dmix plugin instead of hw plugin
# (Exclamation point is needed in order to override the assignment to
# pcm.default in /usr/share/alsa/alsa.conf.)
# Make OSS apps default to using dmix plugin too
/etc/esound/esd.conf - (I use libesd-alsa0)
I use tcp mode because my family have multiple console logins at the same time, and that way they can each use each-others esd if it is running, or start one if needed.
spawn_options=-terminate -nobeeps -as 1
# default options are used in spawned and non-spawned mode
default_options=-as 5 -tcp