yes it works fine now.

first the pc was connected a network, like every other pc here in the company. connected to a domain, received its ip from a dhcp server and so on... luckily the dhcp server was configured to give each pc in the network always the same ip adress.

 now the pc is still on the same network, but i configured it as a dns server. i had to take a static ip adres, so i took the same ip address which was before always automatically assigned to that pc. standard gateway and alternate dns server i also took te same addresses as before.... after that i was able to configure the active directory, and now everything works fine.

 in windows explorer, under my network places i see now two domains: the previous domain of the company PLUS my new domain with all pc's that are member of the domain.

 I hope nothing will explode soon or later? (because i followed no guidelines; only configured everything by guessing. AND most astonishing of all, it works !!!!

 
does anyone sees maybe a potential problem in what i did? (i have to be sure that this configuration will bring no surprises)

thanks