I have additional information.
When I close the lid of my laptop after a while the screensaver comes on.
When I open the lid to work on my laptop I don't have the previous explained problem.
The screen comes up with a nice screensaver.
I have only and always the problem when after a few minutes not working, the screensaver switch on (with the lid open of course).
I hope this will be helpfull ....
Best regards from France.