[jtaylor06]

You may have your connection set to manual where it would probably be a set ip address of for example 192.168.1.2

Vista / 7:
Go to Start, Network, Network and Sharing Center. On the side click Change adapater settings.
Right click on the wireless adapater and click properties.
Click Internet Protocol version 4
then properties.

Set everything to automatic then press ok

This should work

If on XP, it should be Start, Network connections, then skip straight to the bit where it says right click on the adapater