Torsten; when you try to stop the BM-Link and it starts to "wait" - disconnect the powercord or the USB to the beoport - this should stop BM link.
Uninstall BM-Link, reboot and re-install BM link...make sure that you have iTunes 7.42 loaded......connect everything again - check that the BM link logo at the top right is on ON as well - i had a simillar problem and i had to start/stop multiple times in the preference menu before i got it working....Good luck -- Klas