I had the same problem, hooking up to my airport network (128-bit WEP). Fixed it by re-entering my WEP hex key repeatedly until I got it right.

It is (IS ANYONE AT NOKIA LISTENING?) really, *REALLY* annoying to try entering a 26-digit hexadecimal number in a text entry box that (a) replaces every character you enter with an asterisk after a fraction of a second, and (b) doesn't let you paste in a string you typed into another application. It took me about five to eight tries to get it right!

An option to switch off automatic hiding of passwords would be really useful. Let the user decide if they need extra privacy, right?