No after the uninstalling (+ restarting-) the problem was still there.
I normally use pppoe to access the internet - the connection cannot be made - I get a fault report number 814 saying the the underlying lan system cannot be found. In the system-management (ger. Systemsteuerung - not sure of the term used in Engl.) the network adapter seems fine, no yellow exclamation mark next too it.
(Of course I tried to do a system restore… but as this is a dual-boot system with xp - all the vista system-restore points are continually deleted when xp starts. This seems to be a know vista problem that I guess a vista-sp1 will hopefully address.)