Hm, no, I've never heard of this exact problem, but I always just use AIM, as do most of my associates. I do remember, however, when MSN Messenger attempted to allow users to message AIM users. AOL apparently wasn't very happy about this, and would make nearly daily revisions to their network protocols (assumedly) to (try) to prevent MSN Messenger from interacting with AIM users. MSN would then come out with nearly daily updates to MSN Messenger to counter the new counter-measures put in place by AOL. Eventually something apparently got worked out, and MSN Messenger no longer works with AIM users.
I'm guessing something similar has happened now. AOL gets revenue and advertising from the main AIM buddy list, and likely gets angry when another company takes away from potential profit.
I think it's kind of extreme to completely cancel the account for getting caught using 3rd party software, but if you think about it, there's probably many millions of dollars being lost from a few people (well, more than a few) using 3rd party software.
This, of course, is all just my opinion. Someone can go check with AOL if you're ambitious.
