Thank you.
In the mean time I changed back from windows firewall to the third party firewall. I did not change anything. But now the issue does no more accure.
I think Avast was trying to install anything, which was blocked through my third party firewall, but not through windows firewall. (I mean not a programme- Version update, but soemthing else. Emercency update or anything like that).
So I guess: In a few day the issue accur again.