Glad to read I'm not the only one experiencing this; I posted about this very problem last week but I didn't have much information to offer then (I still don't). I too have one computer running OS X and another running OS 9.2. I can't figure out what causes one computer to be unable to surf the net. Both computers will have the appropriate IP address, but at some point after using both to connect to the net, one usually stops connecting - usually the computer running OS X.

I've played around a lot with shutting down one machine, restarting the other, etc, to see if the order of connection with the base station matters (I am using a Farrallon Wireless Gateway Router connected to a Comcast cable modem) - and I can't find any pattern that causes the problem. Although I still remain highly suspicious that it has something to do with using both computers. Curiously, I do not have this problem at work, where multiple computers running OS 9 or Windows and mine running OSX connect wirelessly to an Apple Basestation.

At home, where the problem lies, the only solution that seems to work is to hit the reset button on the back of the Farrollon Gateway. After I do that I can connect using both machines.

Any thoughts on this?
I would greatly appreciate them.