Windows 7: wireless connection doesnt have a valid ip config

howdy,

I've got a very frustrating problem right now and I'm ran out of my own ideas! My network consists of a Belkin N+ Wireless Router, 1 desktop computer that is wired into the router through the lan portion and my computer, a desktop windows 7 home prem. My computer runs wireless thru a wiresless usb stick and have not had problems until the other day.

The problem is: My roomates got rid of their desktop that was wired to the router and bought a laptop. The laptop is new and has windows 7 prem. Now that they have started connect wireslessly my computer is not connecting to the router.
"wireless network does not have a valid ip config" and I have tried to fix this issues many ways. Re-starting router, resetting the router etc... haven't found any help on the net that has been helpful Help!