When I downloaded the newest version of FireFox I also installed the extension Adblock (there's another one that goes hand-in-hand with this one too) - no more shopzilla ad or any ad covering the search feature.
BUT, that being said, you can still use the search feature. Just click on the right side of the box - this places your cursor there even though you can't see it - type the word you want to search (again, you won't be able to see it so spell it correctly
). Hit your "Enter" button and the search will continue.
Also, you can go to another page and search from there - one that doesn't show that banner.