"There are no visible restrictions for ports in Windows-2000-server, but they exists (as we seen)." This is true.In that case, check your postgresql.conf config file for the listen_interfaces parameter, and check it is set to * (i.e. listen_interfaces = *). Then restart the PostgreSQL service if you've had to change it.
Also check your pg_hba.conf, for the "ipv4" lines. Andy