Have you found any patron, or an increase in the number of times of the CTD, when a certain faction is a combatant on the battlemap? If not (If it doesn`t happen with a certain faction only), might it be a problem of a placeholder unit/horse (a captain for example, or a placeholder mount)?

If you have solved the problem with the palm trees sprites, perhaps the solution might be causing it, or maybe even the palm forests themselves are causing the CTD... if you ask me why, dunno, it`s a hunch.

Good luck!