CZJ and JR- falling out?

I just read that Catherine and Julia supposedly had some sort of falling out during the shooting of this movie and still dislike each other. Does anybody know what they fought about. I was wondering as I was watching the movie how they got along. I always wonder how casts get along while filming. Anyway, anybody know what the source of the fight was?

"For the last time honey, there are no pirahannas in- MY BUTT!"- Tarzan