I just used the firebird installer to just install the client components on the workstation. So fbclient.dll is now installed in the system directory. Now it works well.

I had to find a quick solution. I am not realy happy with that, because I realy want to know the reason for the problem. So I will try your suggestion on the weekend when nobody works on this workstation to find out if this was the reason for the problem.

Thanks for your help.

Regards
Helmut