log on delay with windows 2000 server

i have two workstations (windows 2000 and windows XP pro) and one server running windows 2000 server. I have active directory install and setup and both workstations are able to connect to the shared file on the server no problem.

the problem is it would always take about 2-3 minutes for both workstations to log on the server which is really annoying. pls note that these 3 computers are on a private network in which they are not connected to anything else. Please advise.