pekische,
It's great that you are providing this feedback. Thanks mate. But I really need more than the glib description you have provided. I have opened up your save and I'm confronted with this screen.
I can see that you have the force and task edit dialogs open, but I have no clue as to what arty unit you were referring to, nor the sequence of steps you took. A picture is worth a thousand words, especially one that is annotated with an arrow pointing out the unit in question.
Daz's description is a little more helpful but without context as to what dialogs were open at the time I cannot get it to repeat here.
Everyone,
When you are reporting a bug, please let me know what dialogs were open. This can often be done best with a screen dump. Plus I need the exact steps you took. Thanks.