Ah. I mouse-click the Hibernate from the Shut-down menu (right end of Taskbar LXDE), or shut the lid because the Power Manager has been taught to react in that way to lid closing. My LXDE Fn button has produced patchy results so I don't use it. One click, some thinking and whirring goes on, and it hibernates. Press Power, it comes to life and flashes the Desktop, then goes blank-screen until I move or click where-upon the Desktop is back. One man's experience, user results may vary!