I had a similar problem today but not with the beta version. In my case I had a 3c905c card on one client that worked perfectly on my district lan which consisted of 100mbit switch. I found the card was set to 100mbit full duplex instead of auto. Since I was using an old 10mbit hub, you can see why it would not work. You may want to verify the cards in your server and workstations. In my case it didn’t end there. My workstations still would not connect. Like you I get the DHCP……… thing. SO at a console prompt I Typed “service dhcpd stop” enter, “service dhcpd start” enter and finally “xinetd”. And it worked! Don’t know why. I only had to do this once. After several reboots of the server, it worked on it’s own.
Hope this helps.