https://bugs.freedesktop.org/show_bug.cgi?id=41592
--- Comment #7 from mirandir@orange.fr 2011-10-13 09:17:43 PDT --- (In reply to comment #6)
When this happens, can you get a gdb backtrace of gnome-shell and/or the X server process, and attach them here?
I will try, but the problem seems very randomly, and difficult to reproduce.