> If you have firebug at the bottom of your page and resize it, the space > used for firebug is not given back to the website. It stayed white and is > simply displaying nothing.
I remember some people already had the same problem before. Though in their cases the problem was not Firebug but another extension. Unfortunately I can't find it at the moment. So please deactivate your other extensions one by one to find out which one is the culprit.