Mouse events fail to trigger if mouse move too fast

It has been awhile since I have worked in flash.  Right now I am working on something where I would like a panel to disappear when someone mouses off the stage.

stage.addEventListener(Event.MOUSE_LEAVE, leaveHandler);

  It usually works fine but if I move my mouse really fast it doesn't fire.

I have also tried the same thing using a custom invisible button that surounds the perimeter of the stage and I have tried ROLL_OVER and  MOUSE_OVERand again, if I do it too fast my event doesn't fire (I am using trace).

I can't find anything on the net about this - is this typical of flash that if you move your mouse too fast you break it?  Do I need to increase my frame rate (I would really rather not because I have perfectly timed animations - I am at 30 frames per second)

Any help is appreciated!!!!