Comment 1 for bug 1046927

This is a backtrace of compiz when this occurs.

Restarting compiz fixes the problem.

#0 0x00007f643d9a9445 in raise () from /lib/x86_64-linux-gnu/libc.so.6
#1 0x00007f643d9acbab in abort () from /lib/x86_64-linux-gnu/libc.so.6
#2 0x00007f643d9e6e2e in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#3 0x00007f643d9f1626 in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#4 0x00007f6429cc820d in geis_ugsubscription_release_for_device (store=0x1710e10, filter=0x1710b70, device=0x170f340, window_grabs=0x170f200)
    at geis_ugsubscription_store.c:177
#5 0x00007f6429cc6192 in _grail_be_unsubscribe_removed_device (device=0x170f340, gbe=<optimized out>) at geis_grail_backend.c:747
#6 _geis_grail_remove_device (frame_device=0x170f340, gbe=0x16f9988) at geis_grail_backend.c:935
#7 _geis_be_flush_frame_events (gbe=0x16f9988) at geis_grail_backend.c:997
#8 _grail_be_frame_fd_callback (fd=<optimized out>, ev=<optimized out>, ctx=0x16f9988) at geis_grail_backend.c:1021
#9 0x00007f6429cbb426 in geis_backend_multiplexor_pump (mx=0x16f6240) at geis_backend_multiplexor.c:416
#10 0x00007f6429cc0d0c in geis_event_dispatch (instance=<optimized out>) at geis_v1.c:603
#11 0x00007f642a3a27e0 in GeisAdapter::OnWatchIn(_GIOChannel*, GIOCondition, void*) () from /usr/lib/compiz/libunityshell.so
#12 0x00007f643c2c8d53 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#13 0x00007f643c2c90a0 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#14 0x00007f643c2c9164 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#15 0x00007f64387c8cb9 in processEvents (flags=<optimized out>) at /build/buildd/compizconfig-backend-gconf-0.9.5.92/src/gconf.c:1918
#16 processEvents (flags=<optimized out>) at /build/buildd/compizconfig-backend-gconf-0.9.5.92/src/gconf.c:1913
#17 0x00007f643947d59e in CcpScreen::timeout (this=0x1252200) at /build/buildd/libcompizconfig-0.9.7.0~bzr428/plugin/ccp/src/ccp.cpp:430
#18 0x00007f643e2bfe5b in operator() (this=<optimized out>) at /usr/include/boost/function/function_template.hpp:1013
#19 CompTimer::triggerCallback (this=<optimized out>) at /build/buildd/compiz-0.9.7.8/src/timer/src/timer.cpp:227
#20 0x00007f643e2bff5f in CompTimeoutSource::callback (this=<optimized out>) at /build/buildd/compiz-0.9.7.8/src/timer/src/timer.cpp:150
#21 0x00007f643e2bf40d in operator() (this=<optimized out>) at /usr/include/sigc++-2.0/sigc++/functors/slot.h:440
#22 dispatch (slot=<optimized out>, this=<optimized out>) at /build/buildd/compiz-0.9.7.8/src/timer/src/timer.cpp:133
#23 CompTimeoutSource::dispatch (this=<optimized out>, slot=<optimized out>) at /build/buildd/compiz-0.9.7.8/src/timer/src/timer.cpp:131
#24 0x00007f643c7c0f2f in Glib::Source::dispatch_vfunc(_GSource*, int (*)(void*), void*) () from /usr/lib/x86_64-linux-gnu/libglibmm-2.4.so.1
#25 0x00007f643c2c8d53 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#26 0x00007f643c2c90a0 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#27 0x00007f643c2c949a in g_main_loop_run () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#28 0x000000000040241e in main (argc=<optimized out>, argv=0x7ffff3ec1d28) at /build/buildd/compiz-0.9.7.8/src/main.cpp:234