Screen saver or sleep cutting me off from the network


Has anybody noticed this? When I step away from my computer and my monitor shuts off, it appears that my connection to the network gets cut. I'd have a telnet session open in the Terminal and upon waking up, I have to log back in.

I also notice that any AFP volume I have mounted is gone.

Only recently, sleep will make my iBook forget what airport base station to connect to. I have to reselect it.

I wander if this is related?
I know that if I set my iBook up as an ftp server and connect to it (a simple way of backing up my parents PC) I have to turn off the energy saver for system (though you can still leave it set to blank monitor or whatever)