Simple Pan-Zoom flaky behavior

1) Script Title: Simple Image Panner and Zoomer v2.0

2) Script URL (on DD): http://dynamicdrive.com/dynamicindex4/imagepanner.htm

3) Describe problem: I want to include this in my web page at http://www.family.matherclan.com/Test/. It seems to work perfectly in Chrome, but behavior is flaky in both Firefox and IE. In Firefox it only works correctly if the page is RE-loaded after the first load. On the first load the mouse wheel shrinks the image to almost nothing and you can't get it back to the original size. In IE the page works but seems to want to jump to the bottom. I do have another script on the page and don't know if this is causing the problem or not.

Thanks for any help.