Buttons not visible

[Guest Bongo's Basement]

I'm using the following code to display a custom button on my products page for the "add to basket" button (with variations for the wishlist and email friend)...

<a href="java script:submitDoc('addtobasket');" class="icon_basket" style="vertical-align:middle;" ></a>

It was working fine on nearly all browsers but I noticed since I updated to firefox 3.6.8 that the icons/buttons don't show.

You can see this on my website here..

http://www.bongosbasement.com.au/diecast-c.../prod_1304.html

Any help would be grateful.