ActionScript 3.0 :: Prevent Simultaneous Execution Of Multiple Button Threads?

My AS 3 program has multiple buttons. Users can select one and then immediately select another and this causes 2 threads that collide.  Once one button is executing, I want the other buttons to ignore clicks.

The problems are twofold:  1)  the first time the 2nd button attempts to execute (by checking lock), when it returns (from checking lock) and attempts to pick up processing where it left off, it seems to forget where it was and does not utlimately complete its task(s); possibly variables have been altered, it is difficult to say.  That is, AS 3 is unable to successfully pickup where it left off on the first button. the second problem is that AS 3 incorrectly returns to button 2 after the lock condition is cleared.  It persists and will execute that button.