This is with the AIMEncrypt v4 certificate. Breaks when I talk to myself or with another screenname using the same certificate.
AIM 5.9.6089
Windows XP SP2
Middle_Man 0.3.0003
EDIT: The rate limit being green isn't a bug, that screenname is registered as an Open AIM bot.
EDIT AGAIN: Apparently that's what causes the problem: If one or both of the message recipients is an Open AIM bot, encryption breaks (it doesn't break without Middle_Man).
I installed a security certificate. Middle_man only messes up if you IM yourself with in (you get the normal text sent) and the encrypted text sent back to you.
I didn't test it from an encrypted connection to another encrypted connection though, but how rare is that?