Firefox problem

Hi Friends,
I was doing one gallery in flash. It is working fine in IE but in Firefox the first time if we click its not coming properly but after that it is working fine. I m not getting how to fix this?
This is the code i used:

import mx.transitions.Tween;
import mx.transitions.easing.;
spacing = 2;
containerMC._alpha = 0;
border._alpha=0;
preloader._visible=false;
MovieClip.prototype.loadPic = function(pic){
_root.containerMC._alpha = 0;
this.loadMovie(pic);
_root.onEnterFrame = function(){
preloader._visible=true;
var t = containerMC.getBytesTotal(),
l = containerMC.getBytesLoaded();
percent=Math.round(l/t
100);
preloader.preload_bar._xscale=percent;
if (l==t){
border._alpha=100;
var w = containerMC._width + spacing, h = containerMC._height + spacing;
border.resizeMe(w, h);
preloader._visible=false;
delete _root.onEnterFrame;
}
}
};
MovieClip.prototype.resizeMe = function(w, h){
var speed = 3;
this.onEnterFrame = function(){
this._width += (w - this._width)/speed;
this._height += (h - this._height)/speed;
if( Math.abs(this._width-w)<1){
this._width = w;
this._height = h;
new Tween(_root.containerMC,"_alpha",Regular.easeOut,0,100,1,true);
_root.containerMC._x = this._x - this._width/2 + spacing/2;
_root.containerMC._y = this._y - this._height/2 + spacing/2;
_root.containerMC._alpha = 100;
delete this.onEnterFrame;
}
}
};

Here is the link so that you can easily understand my problem:
http://creative.2adpro.com/2adproshop-v2/Web.html

Waiting for your reply

Girish