I am running Windows 10 Pro, build 10586, on a Lenovo T-520. Fairly recently a behaviour has appeared, where the screen locks, and goes blank, after about 2 minutes of not using the PC.
I have checked all power settings, every single one, and nowhere, when on mains, is the PC set to hibernate or sleep after a time shorter than 2 hours.
What could be causing this very quickly triggered screen lock? To unlock, I must use the keyboard or wiggle the mouse to show the lock screen, then click the mouse to show the password input.