Ok, found it out myself: it was the damn vpn client! Version 4.9.00.0050 works but it gives you the KP when shutting down (just read it on versiontracker).
Was pretty hard to remove as it gave me even a KP after typing
sudo /usr/local/bin/vpn_uninstall
in the terminal. Had to do it via a safe boot.
So no vpn for new iMac users... great!