Problem with IE & another with Firefox

I'm using version 1.3.8a of Zen Cart with several mods that I've lost track of. Here is my shop url http://d9studios.net/artshop

I was testing the site in the latest version of Firefox and IE (Firefox 3.5 and IE8) and I ran into two problems.

Firefox problem:
On the Shopping Cart page there is a checkout button but there is no way to click it. Nothing happens. It's just an image. In IE, it works fine. It's only in Firefox that nothing happens. What could be causing this and how do I fix it?

Internet Explorer problem:
On every page at the very top (the header) there is a broken image but I can't figure out what it's supposed to be. This doesn't show up in Firefox, just IE.

Can anyone help me? Please?

The missing image is logo.gif. The easiest way to get rid of the x-in-a-box is find #logo in your stylesheet and add display:none;

Thank you! I checked every file but the css! It wasn't #logo but #logoWrapper2 and I just needed to delete the php information for that tag in the header tpl file.

Okay, IE bug fixed but that very important Firefox bug is still there. :(

Never mind, I figured it out myself.