The gallery shortcode (wp-includes/media.php) outputs incorrect css, I believe.
<style type='text/css'> should be in the head, not within a div.
For local styles it's simply style="border:1px solid green" etc. added to the element.
This is why the gallery looks different between FF and IE - one sees an error, one doesn't. FF shows 1 photo, IE shows no photos.
Tested using 20/11