Why does it seem that whenever I hit auto-attack it targets the *farthest* enemy away from me? I mean, even when I have a nice beckoned clump on the wall and I miss a straggler who's across the room, auto-attack targets the one guy on the other side of the room from me instead of the nice group of guys that are within arm's reach?

Is there a possible bug with the auto-attack system?
How exactly does the system choose the target?