_width is changing the x coords...?

1

I am making a progress bar and most of it works, except when I make the changes the _width property of the mc. for some reason when the incrementation is done on it the x coords is what changes and it races across the screen. I have tweaked it to make the incrementation on the height and it works fine. so I am really lost. Is there a bug that I don’t know about?

Here is the code for the first frame
onEnterFrame = function()
{
var percentC;

percentC = _root.getBytesLoaded() / _root.getBytesTotal();
_root.progressBar_mc.bar._width = 130 * percentC;   //here is where if I change it to _height it works fine
test._width = 130 * percentC;  //test mc on main timeline it works fine, but is a simple object, the other progress bar looks much better

}

Here is the site to see what I mean
http://www.quantics.ca/flash/01_ProgressBar.html

it is the blue scrollbar that is acting funny, the red one is the simple one

Thanks for the help