Problem with loadMovie, 90 degree angle change

So I've been staring at my screen all day, my client getting increasingly irate trying to work out what's going on.

I'm on Flash CS3, AS 2.0

Here's my code:

Actionscript Code:

//set stage for FBF
Stage.align = "TL";
Stage.scaleMode = "noScale";
loadMovie("image.jpg", pic, 'GET');

//define dynamic aspect ratios
picHeight = new Object ();
picHeight = pic._height / pic._width;

picWidth = new Object ();
picWidth = pic._width / pic._height;






//conditional statement to account for various initial browswer sizes and proportions

if ((Stage.height / Stage.width) < picHeight) {
    pic._width = Stage.width;
    pic._height = picHeight * pic._width;
} else {
    pic._height = Stage.height;
    pic._width = picWidth * pic._height;
};  


//center picture on stage
pic._x = (Stage.width / 2) - (pic._width / 2);
pic._y = (Stage.height / 2) - (pic._height / 2);



// create listener
sizeListener = new Object();

// make listener change picture size and center picture on browser resize
sizeListener.onResize = function() {
    
    if ((Stage.height / Stage.width) < picHeight) {

        pic._width = Stage.width;
        pic._height = picHeight * pic._width;
    } else {
        pic._height = Stage.height;
        pic._width = picWidth * pic._height;
    };  
    
    
pic._x = (Stage.width / 2) - (pic._width / 2);
pic._y = (Stage.height / 2) - (pic._height / 2);
    
}

//add listener to stage
Stage.addListener(sizeListener);

My problem is my client wants to be able to change image.jpg occasionally, to ones of different size ratios. If the "pic" movieclip has a box of the right size ratio inside it I have no problem unless I change the image, which I need to be able to do. If there is nothing inside the movieclip when I load it, the image always appears on its side, and I can't seem to get it rotate to the correct position!

Please help if you can - I'm desperate!