Gnome 3 has a screen saver (or more accurately a screen blanker — there are no pretty pictures) which is turned on by default and which password-protects (locks) your desktop by default when it activates. Unfortunately it’s been known to be buggy since it was released as part of Gnome 2, often refusing to unlock your screen and forcing you to reboot your system.
Users of the Gnome 3 desktop shell are reporting that for some video card and monitor combinations the Gnome 3 screen saver, after getting a key press / mouse movement that should prompt you for your password to unlock the screen:
- Won’t unlock the screen at all.
- Will display a mouse pointer but no password prompt.
- Will display your original screen and all open documents (without prompting for a password) but will not allow you to click on anything, basically appearing as a locked-up desktop.
My setup reliably produces situation #3.
To unlock a locked-up desktop:
- Ctrl-Alt-F1 will give you a text-based terminal login.
- Log in with your user name and password.
- Type: “killall gnome-screensaver”
- Ctrl-Alt-F7 to get back to the (now unlocked) Gnome 3 desktop.
To replace the Gnome 3 screen saver with something less buggy:
- Activities > Applications > Other > Synaptic Package Manager
- Quick filter: xscreensaver
- Right click ‘xscreensaver’ and select ‘Mark for Installation’
- Click ‘Apply’ to install
- Activities > Applications > System Tools > System Settings > Screen
- Set “Turn off after” to ‘Never’ and “Lock” to ‘OFF’. This disables gnome-screensaver.
- Activities > Applications > All > Screensaver
- Follow the prompts to activate xscreensaver
If you try to uninstall gnome-screensaver Synaptic Package Manager will also want to uninstall gnome and gnome-core, which is a bad idea if you want to run Gnome. Gnome will always start gnome-screensaver even if you have it disabled, and xscreensaver won’t run if gnome-screensaver is running. So you basically need to kill gnome-screensaver after Gnome has started and then start xscreensaver. You can do this by adding a startup program:
- Activities > Applications > Other > Startup Programs > Add
- Name: “Screen Saver”
- Command: “sleep 30; killall gnome-screensaver; sleep 5; xscreensaver”
- Comment: “Kill gnome-screensaver, start xscreensaver”
- Click “Add”
Hope you find this useful.