AOL's instant messenger is blocking Trillian
AOL is apparently not interested in AIM users gaining access to their AIM via other multi-messengers such as Trillian and only using one interface for many messengers. AOL is thus blocking 'Trillian'.
The recently released version of Trillian was supposed to bypass this protection from AOL, but AOL has apparently followed suit and again blocked all customers who use Trillian. Then Trillian released a new version and you can use the AIM again in the latest version (0.7.21). Whether there will be a constant back and forth between AOL and Trillian, or whether an agreement or solution will soon be found, is at least in the stars for the moment. (News slightly adjusted)