On my machine, the screen locks automatically after a short period of inactivity. While this is a neat security feature, it is a bit pointless for those who live alone. However there does not seem to be any configuration for the screen locking. Reproducible: Always
The setting can be found in System Settings -> Workspace Behaviour -> Lock Screen
It should probably grouped together with "Things that happen if you don't move your mouse" instead.
(In reply to Salvo "LtWorf" Tomaselli from comment #2) > It should probably grouped together with "Things that happen if you don't > move your mouse" instead. That might be Power Management, but not everyone may look for it there (since it is not really a power management feature). We are currently planning a redesign of the System Settings application (not the individual modules, but the general shell) anyway, which should help make it easier to find modules even if they are not in the category that you personally expect them to be in, so hopefully thiatwill help.