I doubt AA is at fault, we both had a predictable crash on 2 different machines after a certain time. I replayed the battle 3times with the same result.
My ingame AA is even disabled, cause I use an external modification (currently testing FXAA).
I tend to crash more often with uber-high settings, though ^^ but more or less in epic battles with lotso units.
YES! Cause I couldn't let it go and tried some weird stuff: deleted Trebuchet & bombard, cause I expected some aiming issue and voilá it worked! I might wanna check further, if that is really the problem and might test it with either one of those deleted 
proof: (darn and I thought the hvy boyars would r*pe me ^^)