I hear there are lots of problems when trying to join a strategus battle or server. One of the problems is the annoying "Incorrect authorization key" message. This is a quick and easy way to (temporary) solve it. It doesnt work all the time.
--> Click start --> type in the search box 'cmd' (without the '') , select the program showing up, right mouse button and "run as administrator".
(-->Click start -->run -->cmd -->hit enter.) (Windows Xp)
--> type in the following command exactly as written:
ipconfig /release (disables your internet connection)
-->hit enter and wait a few seconds. Then type the second command.
ipconfig /renew ([re]enables your internet connection)
Note: make sure you type a 'space' between "ipconfig" and the "/".
This will drop your internet connection and change your dynamic IP, it only works on machines with Windows as operating system. If this doesnt work i can only sugges the following: - You might try to reset your router/modem/etc
- Contact your ISP or a developer/admin.