Just to remind you, that if you have a Saucy (or Raring) setup with gnome-shell from official repos (version 3.6.3),
do not install new clutter-1.0 (1.14.0-1).
It will break both gdm and gnome-shell. Gdm will freeze and you are not able to login. X will also freeze, so startx will not help there.
However, you can still login from tty1 (Ctrl + Alt + F1).
You can sort this issue by downgrading clutter packages to the previous version (1.12.2).