Linksys Wireless G, same one I use. Caused me many problems in the past, and still occasionally wants to go haywire.
Anyways, go up to your routers menu, (192.168.1.1) and make sure the settings are correct. I would suggest you change WEP to PSK2 as well or if you would like to avoid problems at a higher risk then disable it. Also, check if you have it set to Wireless - G only or All Cards.. that can mess it up as well.