Instances disappearing

Well this is the thing, I have an array of Moviecclips, and I want a random movieclip from that array to appear on stage every certain amount of time.

I made a class that adds a child to the variable, the problem is that sometimes the instances disappear.

here's the code of the class:

import MC1 //the movieclips
import MC2
import MC3

public class theclass extends MovieClip
{
     var arrayA:Array = new Array(MC1,MC2,MC3);
     var containerM:MovieClip;
     var Speed:int = 7

     public function theclass()
     {
          containerM = arrayA[int(Math.random()*3)];
          this.addChild(containerM);
          addEventListener(Event.ENTERR_FRAME, eFrame);
     }
     
     private function eFrame(event:Event):void
     {
          this.x -= Speed;
          if(this.x < 0 - this.width)
          {
               removeEventListener(Event.ENTER_FRAME,eFrame);
               if(this.parent)
               {
                    this.parent.removeChild(this);
               }
     }

Now I call it from stage:

var min:int = 0;
var limit:int = 40;

function repeat(event:Event):void
{
     min++     
     if(min>= limit)
     {
          var MoC:theclass = new theclass();
          Moc.x = stage.stageWidth;
          Moc.y = stage.stageHeight/2;
          addChild(Moc); 
          min = 0;
     }
}

stage.addEventListener(Event.ENTER_FRAME,repeat);

So here's basically the code, so can anyone tell me why the instance disappears before getting to the other side of the stage? or what's the problem?