Swf clip alignment please help

Hope someone can help me to figure this out
I have a full browser gallery that loads external images from a xml file
I also have a movie clip on the main timeline that I dinamically aligned to the center left of the browser using this code:


Stage.scaleMode = "noScale";
Stage.align = "TL";
setStage();
var stageListener:Object = new Object();
Stage.addListener(stageListener);
stageListener.onResize = function() {
 setStage();
};
function setStage() {
 var WIDTH:Number = Stage.width;
 var HEIGHT:Number = Stage.height;
 about_page._x = 0;
 about_page._y = HEIGHT/2 - (about_page._height /2);
}

However, when I preview the movie, the swf does not appear aligned, but if I resize the browser even 1 inch then the swf alignment works!!!
It is driving me nuts…
Can someone please help me to work this out?
I have attached my .fla, my background img and my xml in case someone wants to take a look