It sounds like one of the laptops is trying to grab and IP already assigned to another device...or is statically configured as such.
check your ips using the cmd Frank mentioned...also, using the laptop that DOES connect to the wireless network type the following command into a command prompt
This will give you all the devices currently on the network (IP and MAC). The result should be something like this:
Interface: 192.168.0.154 --- 0x3
Internet Address Physical Address Type
192.168.0.8 00-10-4b-21-4a-0e dynamic
192.168.0.254 00-c0-49-aa-6a-0f dynamic
See if any of the IPs in the arp cache are the same as the laptop that can't connect.