I am using Windows 8.1 at work, and for the past week or two, my computer keeps getting locked after about 13-16 minutes from the last time.
It doesn't matter that I am constantly working on it. It can happen while I type something on the keyboard, or while I use the mouse to browse the internet. The screen just suddenly goes dark, and when I move the mouse again, I get into the lock screen, and I have to put in my password to keep using my computer.
I discovered that when I restart the computer, the trouble seems to go away, but the next day it returns. Maybe it has something to do with the fact that the display is being turned off over night, while the computer is running.
I tried changing the "Put the computer to sleep" setting in the Power Options, and switched it to "never", but that didn't solve my problem. I also tried disabling Remote Access, thinking that maybe some remote computer was trying to access my computer on a regular basis, which kicks me out locally.
I am also using the Chrome Remote Desktop app, so maybe this could cause some problems?
I looked through my eventlog, and saw nothing out of the ordinary.
I used to have the same problem before, on Windows 8, so I don't think it's related to the 8.1 specifically. I don't know how I fixed it in the past, it just seemed to resolve itself after a while.