Yes, we installed NavisWorks on a new workstation.
On this PC we installed the LMTools and used the Network License Activy Utility to receive our new network license. That all works fine.
So NavisWorks runs nice on that PC (actually 64 bits, Windows XP!). Because it runs the service and NavisWorks. Anyhow, now the other pc's have to connect to this new server.
Finally we found it. Still at the workstation with the LMTools running, the Microsoft Windows Firewall had been turned on. When turning this off, everyone can use the NavisWorks licenses again!
Now, I have to find out what ports have to be set for the firewall.