Comment 17 for bug 641554

@Omer , didrocks mentioned getting a *gdb* and running that command under gdb.

have a look at: <https://wiki.ubuntu.com/Backtrace#Generation> ,
From a desktop session, you have to start gdb with:

 gdb mutter 2>&1 | tee ~/gdb-unity.txt

 and then in the arguments is :
(gdb) run --replace --mutter-plugins=/usr/lib/mutter/plugins/libunity-mutter.so.0

and as didrocks mentioned , we need to install the debugging symbols