Thank you, can you offer any more information that might help me reproduce? I don't usually play with the mouse mode, so I'll do some extra testing there to see if it's related. Is there a particular strategy you usually use? Do you usually put on fast-forward? Is the minion still animated and do they get targeted by the towers? Could there have been a particular minion on the screen at the time, like maybe lich?
edit: Also, do you play on the web or windows download?