Help with isolating specific keys

Hi, I'm using the script below to isolate specific keys on the keyboard to control the timeline. This works for a while but seems unstable. It causes Flash Player Debugger to run slow and eventually hang and I have to force quit the player.

Any suggestions to help to improvewould be grateful.

stop ();

var keyListener = new Object();

Key.addListener(keyListener);

keyListener.onKeyDown = function ()

{

    if (Key.getAscii() == 8)

    {

        gotoAndStop(7);

    } // end if

};