Windows 2000 slow to start

[rjdscs]

I have just installed a small windows 2000 network with a windows 2000 server (PDC) and 4 windows 2000 proessional workstations. The proplem is that when internet access is available, i.e. the internet router is switched on, the windows 2000 professional workstations take an excessive amount of time to startup, and sometimes never get to the ctrl,alt,del screen. As soon as the internet router is switched off the ctrl,alt,del screen will come up.

Any ideas what they are accessing the internet for, and obviously waiting for a response, and how do I stop them?

Thanks

Richard