DHCP Issue

Running a wireless network w/ 12 In Motion and Fujitsu tablets, all clients
are running Intel Wireless 2200BG card and the access point is Cisco Aironet
1200. Set the clients to get IP via DHCP, all of them works except for 2.
As soon as I assign a static IP, they connect right to the network, so it's
not the network security that is blocking them. Any idea if there is
anything in Windows that is stopping these 2 from DHCP?

Thanks in advance.