gistfile1.txt

Index: wp-admin/nav-menus.php
===================================================================
--- wp-admin/nav-menus.php  (revision 23446)
+++ wp-admin/nav-menus.php	(working copy)
@@ -264,6 +264,8 @@
 		// Get existing menu locations assignments
 		$locations = get_registered_nav_menus();
 		$menu_locations = get_nav_menu_locations();
+		if ( empty( $menu_locations ) || ! is_array( $menu_locations ) )
+			$menu_locations = array();
 
 		// Remove menu locations that have been unchecked
 		foreach ( $locations as $location => $description ) {