iChat connection problems

So I've been having the most frustrating time connecting to iChat. I have ruled out my router being the culprit as I have plugged directly into the cable modem and get the same error; "Could not connect to AIM: The connection to the host was unexpectedly lost". Anyway, I also tried stopping my mac fire wall and allowed the ports listed by apple in the firewall settings, none of that worked either. I have tried using both the AIM client and iChat but with no success. It appears as if it has something to do with the internet service provider, but what internet service provider in the right mind would make it difficult for people to access something as universal as instant messaging services. Anyway, any insight or assistance would be greatly appreciated.

I happen to have the exact same problems. I think I can rule OUT the ISP, as I'm able to instant message via GAIM on my other 'puter under both XP and Linux.

I think there's a bug. Usually what causes iChat to go whacky on me is if I put a URL in an instant message.