Mc Help

okay, one last question (i hope) before i'm off to sleep.

i have a movie clip with a transparent button over it,
and i am using this script to turn the mc into a button

code:
on(rollOver){
orb_main_mc.gotoAndPlay("_over");

}
on(rollOut){
orb_main_mc.gotoAndPlay("_out");

}

my problem is that if the mouse rolls over then rolls out too quickly (before the mc gets to the stop(); frame), then it acts all wierd, and does a "reverse mouse over" but with no animation.

help?

thanks,
chris