Windows clients don't recognize DHCP server automatically

Hi all, I am trying to configure a DHCP server on SUSE 9.2 Pro in a small private network. Everything works so far except that Microsoft Windows clients don't seem to recognize the DHCP server automatically when they are plugged into the network. I always have to run "ipconfig /renew" from the DOS command prompt. With other DHCP servers, this is not necessary. Is there any option in dhcpd.conf which I have to set? Thanks for your help, Benjamin