Help!! Airport stopped working!

Is there any way to roll back settings for the airport card? I was connected to the network until I started to try and network with a PC, and now airport constantly says authenticating.

When I first got the mac, all I had to do was turn on and it would connect, not even a password for the first time I used it.

Any help would be great.

I'm on an iBook 1.33 GHz 14"

Sorry about this, but it's just somehow fixed itself. Not sure how, but I don't even wanna touch anything now. Oh, thank god.
Don't ya just love macs?