Mouse event ROLL_OVER and ROLL_OUT clash


I have a little complicated set of ROLL_OVER and ROLL_OUT event handlers which are getting clashed.

I have following movieclip symbols on the stage:
Bounds (child of Background)
Design (child of Background)
Circle1 (child of Background)
Circle2 (child of Background) *

Design and Circle1 should get displayed when the mouse rolls over Bounds.
Similarly, Circle2 should get displayed when the mouse rolls over Circle1.
Circle1 and Circle2 are concentric and Circle2 is bigger.

Now, the problem is that, when the mouse cursor is rolled over on the common area of the two circles, the event handlers (ROLL_OVER as well as ROLL_OUT) of Bounds and Circle2 get called continuously.

I tried to get rid of the event handlers for Bounds under the ROLL_OVER event handler of Circle2 by using removeEventListener() but to no avail.

Any hints?