Dell WLAN cannot connect with static IP

[tpadowner]

I have a local car dealer that purchased 5 Dell Latitude D630 Core 2 RAM 2 GB - 802.11g - Win 7 Pro 32-bit OS.

Two laptops have the “Intel(r) Pro /Wireless 3945abg network card and 3 have the Dell Wireless 1390 WLAN Mini-Card

He has 2 networks in the dealership

One for customers to use which is secure - it is set to DHCP - WPA2-Personal
One for the dealership - it is set to Hidden and uses Static IP addresses - WPA2 Personal

All 5 machines can connect to the customers network using the network key. I also had them in my office and they all connected to my network which is WPA2 as well

The 2 with the Intel cards can connect to his dealership network employing the static IP without problem.

The 3 machines with the Dell Mini-Card cannot connect to the dealer network using the static IP.

All machines are set as follows

Connect automatically when this network is in range
Connect to a more preferred network if available
Connect even if the network is not broadcasting its name (SSID)

Are there any network gurus out there that can give me an idea on what to pursue next here?

Thanks very much