Hi ! The problem has been solved, icapturied network traffic showed that Samba for some unknown reason insisted on a re-election of the Master Browser every 2 seconds or so. Of course, name resolution broke down completely. After switching off Samba, the situation became normal again, even after re-activating Samba. Thanks for all the help, I learned a lot ! Though I still wonder why any clients seems to be able to initiate an election. Does this make sense ? Thanks, Jörg