DHTML and image maps

I'm having a bit of a problem with a site I'm currently developing. I'm using DHTML to create a pop-up type menu. When I click on an image the menu shows up. When I click again, it disappears. The menu that shows up is one image using an image map.

The site seems to work just fine in Netscape 4.7 and IE 5.0 but when I view it using IE 4.0 on my home computer the image map doesn't work. The menu image shows up and I can click on the different sections of the image map but the links no longer work. I stay on the same page.

The site is here. Link to the JavaScript .

I've looked at the code quite a few times and can't figure out why the image map stops working in IE 4.0.