Problem with 404 error message and search box

For some reason I’m getting a 404 error message followed by a large search box in the main content area of the ‘Home’ page – how do I stop this from happening? Some info that might help is that in the WP control panel ‘Home’ does not appear in the pages list but it does show in the menus list.
Another issue I also need resolved is that the page title shows below the menu bar if I go to another page. here is a screenshot of the Home page.

Thanks if anyone can help.