Beyond the discussion that WEP is not secure (I can now hack it in under 2 minutes) there is that other issue that if you get the password wrong it won't complain and what happens is exactly what you ask about.
The fix for both is simple. Take the Cnet Networking Forum advice and move up to WPA or WPA/WPA2.
Well here goes...
My ZyXEL wireless was working perfectly until yesterday when I bought home a beautiful new iMac and now everthing has gone wrong with the internet!
Heres the thing... the adapter is plugged into a windows main computer. It says that it has full signal, but cannot connect to the internet, it says connection problem 3? Also, it is not connecting to my iMac at all now. For a few minutes it was working fine then just didnt.
HOWEVER the wireless is working fine on my laptop (which im on now) and connecting to my iphone.
I've tried everything with WEP, restarting the wireless box, passwords... bleh everything. I really need it fixed!!
I do not have the box or disks for the wireless box. Which sucks i know.