Image thumbnail scroller doesn't initially show all thumbnails

I am using an image gallery from a Kirupa tutorial that uses a horizontal scrolling thumbnail area. I edited the gallery as needed but am having a problem with the way the thumbnail strip looks. When you first go to the gallery (before touching the thumbnail area, which automatically scrolls when you mouseover), only 2 of the thumbnails are showing and they are all the way to the right (the first thumbnail should be all the way to the left). When you mouseover, the thumbnails scroll until they hit they hit the left side boundary. Then you scroll the other way and the first thumbnail is then anchored where it should be. You can see what I’m talking about at

What do I need to do so the thumbnail bar is “full” when you open the page?
I am using an XML file for the images.