Have you both installed the latest patch from microsoft? I think I read somewhere that the latest patch has been causing trouble with AIM. I looked everywhere I could think of but can't find it. Otherwise, I have no idea at the moment. Zonealarm should tell you what ports the program is trying to use to make sure you have the right ones forwarded on your router.
Comments
My friend and I cannot get it working either. We can connect to send pictures and files, but not for video or audio communication.
Assuming you have the same symptoms, I'd say it's a bug in AIM.
KingFish