Strange menu on one column layout

There is a strange drop down scroll menu that appears in my main menu when choosing one colum layout. It goes away when I choose 2 or 3 column layout. (link to print screen: https://www.fitbyemmaha.com/wp-content/uploads/2015/09/Sk?rmavbild-2015-09-01-kl.-03.12.11.png )

What can I do about it?