Processing empty search TwentyTen

On my website (which uses a child theme of TwentyTen) when you submit an empty search box it takes you to a page that says nothing found however the navigation menu isn’t displayed but it does when you enter a search term (whether it finds anything or not). How do I change it so that if a person submits an empty search it either doesn’t do anything or takes them to a nothing found page with the navigation menu displayed. If I am correct it is loop.php that needs editing but I have tried different things based around my searches on the internet with no result please could someone help me with this problem?

Thanks