[Plugin: Email newsletter] Change Submit to Image

Oh I’m usually good at this.

I’m using the plugin Email Newsletter
http://wordpress.org/extend/plugins/email-newsletter/

I made the submit button an icon but in IE it shows a little box around the image with a dead image icon on top of the actual submit button icon. ( http://i298.photobucket.com/albums/mm256/barefootmarket/error2.jpg )

In other browsers it looks fine, but there is a gray box around the image.
( http://i298.photobucket.com/albums/mm256/barefootmarket/error1.jpg )

I see nothing in that plugins css that calls for a gray around an image.

Ideas??