I have a computer, I think it's running GNOME (it's running whatever the default is; I have the Unity panel,) and I installed LXDE for use on another user, but after installing LXDE, it will no longer lock the screen due to inactivity, or for any other reason.
When logging in, I have to enter my password, just like normal, but the screen cannot lock. Wait 5 mins (my setting, have verified this,) still unlocked. Press CTRL-ALT-L, no response. Even going to the gear and choosing "Lock Screen" has no result.
Even after deleting the second user account (just on a hunch,) the screen STILL cannot lock.
What do I need to do?