Thanks for Your advice ...
Starting I did consider having mechanically made something wrong...
... later I felt that it may be a sign for Windows 10 consuming more cpu-capacy /Systemcapacity/ memory than the system may be prepared to offer...
- I have tried Intels graphic driver update - Intel does stop, as it finds its chips modified by lenovo.
- Lenovo does not seem to care much, drivers have not been updated for quite a long time.
- Keyboard and Touchpad drivers from Lenovo had been installed & updated.
I had this experience, as I upgrade our family-travel-notebook and at the same time prepared the "older" and a third one, made of spares, for sale.
The older one had been installed via Windows 8.1, to Windows Pro and been in use for over a year, traveling to southeast-asia and New Zealand,
the spare one was immediately installed Windows 10 Pro, The newer one (different systemboard) the same way.
So, I do think, it has to do with Windows 10,
- maybe the update-process,
- may be capacity comsumption on Update and later restart, possilbly for more than one start...
But:
It happend - once - that starting into the systems boot-menu, the keyboard even on system-level did not work.
As for now: They are on their way to Win 10, V. 1903, Classic shell seems on the verge of being tossed out by MS ... That woudl be sad and it could become a problem as I totally dislike the Windows10-Boot-scene..
Happy trails, no more trade-wars, no hot military conflicts... we (Europe) had enough of that stuff the last 150 years!