Can you add "User Switcher" - "A menu to quickly switch between users" applet to your panel, then right click on it and select "Preferences" and see if "Lock the screen after switching users" is on?
-- Switching back to an user account needs no password https://launchpad.net/bugs/89219 -- desktop-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
