Computer-owned units keep running back to starting location

Level 7
Mar 2, 2008
As the title says, if I order a computer-owned unit to move somewhere, it will just run right back to where it was.
I didn't start melee AI, and I can't set them to neutral, because I want them to cast spells as well.

Halp! :cry:

EDIT: If one unit gets to exactly the location ordered, it will stay there. Any units obstructed in any way just run back to their original location. :bored:
editing the "creep - guard..." options in gameplay constants did nothing.