Hi, I am a pretty new Linux user. I am running Ubuntu Mate 18.04, on a Lenovo ThinkPad x250 laptop. Getting it up and running has generally been very smooth, but I have run into a problem with the screen going black after keyboard/mouse inactivity for about 10-15 mins (including watching video).
This didn't seem to be the case originally, and seems to be a problem that has developed in the last few days.
When the screen goes black, the computer seems to still be working (audio from video continues, and can be started/stopped pressing the space bar, and audio can be turned up and down with the relevant buttons) but I can't wake the screen by pressing the keyboard keys or moving/clicking the mouse, or by hitting the power button.
After digging in forums, I had a go at pressing the Ctrl + Alt + F1 key when the problem occurs, and this does take me into a terminal screen ok, and then I can get back safely to the GUI by pressing Ctrl + Alt + F7, so overall I won't be losing unsaved work with the problem. However, I would like to be able to control power management (and I'd really like a nice screensaver!)...
I've tried changing settings in the Screensaver and Power Management preferences in the Control Centre, but these don't seem to have any effect. I've tried lengthening the "Regard the computer as idle after" time in the screensaver panel, but this doesn't seem to make any difference, and in fact the screensaver doesn't kick in even if I set it shorter than the time that it takes for the screen to go to black... I've tried unchecking the "activate screensaver when computer is idle" and "Lock screen when screensaver is active" checkboxes. I've also made sure that the "Put display to sleep" time in Power Management is 1 hour.
I did install the xscreensaver package, and for a while this was working fine; it's only more recently that it seems to have become a problem.
Does anyone have any ideas about what the problem could be, or what I might be able to do to sort this out?
With thanks in advance, and apologies if there is already an answer to this somewhere that I couldn't find.