Comment 1 for bug 888779

I couldn't find anything in /usr/bin, but then I tried `grep -r nberra` /etc`. I have
  /etc/X11/Xsession.d/52libcanberra-gtk3-module_add-to-gtk-modules
  /etc/X11/Xsession.d/52libcanberra-gtk-module_add-to-gtk-modules:
both adding "canberra-gtk-module" to GTK_MODULES, and sure enough

  % echo $GTK_MODULES
  canberra-gtk-moduleanberra-gtk-module

That explains why GTK apps are trying and failing to load this garbled library!

(BUG!) I don't see how the environment variable gets garbled every time I restart, perhaps there's a race condition (in the X display manager?) loading the two sourced Xsession(5) files?

It turns out I have both
  i A libcanberra-gtk3-module - translates Gtk3 widgets signals to event sounds
  i libcanberra-gtk-module - translates Gtk+ widgets signals to event sound
installed. (BUG?) Do these packages conflict? `aptitude show` says each conflicts with itself, which seems weird, but I'm no packaging expert.

It sounds like Debian upstream may be getting rid of the Xsession files that fiddle with GTK_MODULES in libcanberra-0.28-3, see bug http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=622992

To sum up, the workaround is probably to uninstall one of the libcanberra-gtk{,3}-module packages, but as usual there may be other bugs lurking: the corruption of GTK_MODULES and a packaging issue.