Playing random movieclips via timeline

Question

I have a project that is eight frames long on my main timeline. On each frame is a different movieclip with nested animation that play for varying lenghts. I want to play the animation on the first frame. Then, once a button is clicked, randomly load one of the movieclips on frames 1-7. Please see the following screenshot for a view of my main timeline.
On that first frame I have writtent he actionscript command stop(); I have also told each movieclip to stop on the last frame of the nested animation and return to frame 1 of the main timeline so the process can start all over again.
Within the first movieclip is the following actionscript to define how the button behaves and load the random animation:
boxButton.addEventListener(MouseEvent.CLICK, onBoxButtonClick);
var randNum:Number=Math.floor(Math.random()*8)+2;
function onBoxButtonClick(event:MouseEvent):void {
                    MovieClip(root).gotoAndStop(randNum);
Everything works perfectly, exactly how I want, EXCEPT, once the button is pressed, my movieclips seem to play at varying speeds. Sometimes they play perfectly, other times they go by in the blink of an eye. Any idea why this is happenning and how to control it? I want everything to play at 24fps.

Answer 1

La velocidad a la que corre un Movie Clip se debe principalmente a la memoria disponible que tiene la maquina, y los elementos usados por la pelicula.
frames 1-7
I don't think it has to do with the memory on my machine- I tried it on a couple different computers.