Yea, that's because the jQuery issue is not picked up in Firefox.
The only other thing you can do is look at the other libraries you are calling and try put in something like this

<script type="text/javascript">
var $j = jQuery.noConflict();
$j(document).ready(function() {
$j('#gallery a').lightBox({fixedNavigation:true});
});
</script>

I know that's a bit vague but that is where the problem is. A conflict between mootools which is built into joomla and jQuery.

You might get something from this, I haven't tested properly but maybe it might put you in the right direction.

www.blog.highub.com/cms/remove-mootools-from-joomla-header/


Will

sorry i think i'm not so smart... where shall i try to put this code?
..thank you..

well, i don't fully understand it myself but the script that i posted last, that is another jscript library that was conflicting with Mootools. So I used jQuery.noConflict infront of it when i called it.
You would have to find the php file where Request Connection and ProfileBook are being called from.
It might already have $ infront of it. But $ is used on mootools also so what i did was declare $j as jQuery.noConflict and replaced $ with $j.

Maybe the best thing to do is do some reseach on jQuery.noConflict() to see how it is used.

if you mean the code shown in the link i provided, then this should be copied into the template index file anywhere within the head. But use the second script (the one to remove only mootools) because you need the jQuery library.

Unfortunately you cannot remove mootools completly from the site because it's used in the Admin panel.