horse pulling back when tied

["spencer" <spencer@inu.net>]

My green broke 9 yo Arab mare still has days when she pulls back all the
way on the halter when tied to solid post, etc.  Anyone have any ideas or
experience to correct it so we don't look too uncivilized at the endurance
rides?  If a pressure is placed on the lead rope or halter she pulls all
the way to the end and this am managed to fall down in the process. 
Thanks.
Mary Ann
Zavalla, Tx