login always returns to login

[robert]

Hi there


I am using ubuntu 19.10

for some times now, I have the problem, that my login process seems to log in 
properly, but the switches back to the login screen.

This is irrespective of which user I am trying to log into.

So in fact I can do nothing.

When I start in the recovery mode, and then from there go in to "full login", 
every thing works fine.

Can anybody give me please a hint, how to fix this?


thanks

Robert