WHAT DID I DO WRONG ............... DHCP

I AM RUNNING A DHCP SERVER WHICH OTHER CLIENTS CONNECT TO IT TO GAIN INTERNET CONNECTION. BUT ALL MY SYSTEMS WERE ASSIGNED IP ADDRESSES AUTOMATICALLY.... BUT THERE IS THIS PARTICULAR SYSTEM THAT HAS REFUSED TO CONNECT I HAVE SHUT DOWN FIREWALL BUT IT STILL HAS NOT CONNECTED....... WHAT DO I DO..... OR COULD IT BE THE NETWORK CARD.... COS ON MY OTHER SYSTEMS WHEN I FINISHED INSTALLING OS (XP SP1) IT STARTED BROWSING AUTOMATICALLY..........

WHAT DO I DO....

THANKS

N.B

(I AM USING A CLIENT / SERVER CONNECTION)

check the IP address this machine has when it does not connect. check the health of the network card as well.