As you're looking at the fortress from the gates on, the first ladder on the left is occassionally difficult to climb. It seems the transistion for it is actually behind the ladder, and if you don't realize this, you may run back and forth in front of the thing, getting AoO's the whole time. I have seen people die because of this ladder in what seems to be an ooc issue (unless that particular ladder is a bitch to climb for some reason). The other ladders never seem to give anyone a problem.

I've noticed the same thing.

This is an issue with all ladders I think.

It stems from the fact that you cant actually click on the foot of the stair placeable to climb, instead you have to be as close as possible to the centermost point of the placeable, in order to use it and activate the script that moves you from the bottom of the letter to the top.

Easy IG solution is to mouse/wasd move behind the ladder before climbing.

The issue in this specific case though is probably that terrain is in the way and keeps pathfinding from moving the character close enough to the placeable.

Simple Toolset solution would probably be to move it an inch to the side or something.