This work around works for me when the bug hits: Use Ctrl-Alt-F1 to get a text login prompt and login as the same user that you were using with Unity/Gnome. Use top to find the process number of the screensaver process. It will likely be at the top of the list as it will be running 98-100% CPU utilisation. Issue kill -9 on the process. Logout and switch back to your GUI session using Ctrl-Alt-F7.
This work around works for me when the bug hits: Use Ctrl-Alt-F1 to get a text login prompt and login as the same user that you were using with Unity/Gnome. Use top to find the process number of the screensaver process. It will likely be at the top of the list as it will be running 98-100% CPU utilisation. Issue kill -9 on the process. Logout and switch back to your GUI session using Ctrl-Alt-F7.