Question When I type something, Windows blacks out and then lock screen

[ToxicThing]

So I have this I would say unusual problem. On my DELL laptop, when I type something in for example Microsoft Word, sometimes Windows would suddenly go black screen, and after about 5 seconds show lock screen and I have to press enter (not enter password like on startup) to go back to writing.
One time this happend for 4 times in a row, it would go black, lockscreen, press enter and immediately when I start typing, goes black again and all over again.
Most of the times I can use laptop without this bug, but I would like to get it fixed.
Does anyone have any experience with this problem?
Thanks

 

[Colif]

Try a clean boot and see if it changes anything - make sure to read instructions and make sure NOT to disable any microsoft services or windows won't load right - https://support.microsoft.com/en-au/help/929135/how-to-perform-a-clean-boot-in-windows

it doesn't delete anything, just stops non microsoft programs running at startup.

if clean boot fixes it, it shows its likely a startup program. You should, over a number of startups. restart the programs you stopped to isolate the one that is to blame.