I also have this problem. My solution has been to toggle the Terminal (Ctrl + Alt + F1) and then toggle bock to Gnome (Gtrl + Alt + F7)
Linux Orithyia 3.13.0-24-generic #47-Ubuntu SMP Fri May 2 23:30:00 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
GNOME Shell 3.10.4
I also have this problem. My solution has been to toggle the Terminal (Ctrl + Alt + F1) and then toggle bock to Gnome (Gtrl + Alt + F7)
Linux Orithyia 3.13.0-24-generic #47-Ubuntu SMP Fri May 2 23:30:00 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
GNOME Shell 3.10.4