Index: wp-admin/includes/nav-menu.php
===================================================================
--- wp-admin/includes/nav-menu.php	(revision 18318)
+++ wp-admin/includes/nav-menu.php	(working copy)
@@ -1085,8 +1085,9 @@
 function wp_get_nav_menu_to_edit( $menu_id = 0 ) {
 	$menu = wp_get_nav_menu_object( $menu_id );
 
-	// If the menu exists, get its items.
-	if ( is_nav_menu( $menu ) ) {
+	if ( is_wp_error( $menu ) ) {
+		return $menu;
+	} elseif ( $menu && ! empty( $menu->taxonomy ) && 'nav_menu' == $menu->taxonomy ) { // If the menu exists, get its items.
 		$menu_items = wp_get_nav_menu_items( $menu->term_id, array('post_status' => 'any') );
 		$result = '<div id="menu-instructions" class="post-body-plain';
 		$result .= ( ! empty($menu_items) ) ? ' menu-instructions-inactive">' : '">';
@@ -1121,11 +1122,7 @@
 		$result .= walk_nav_menu_tree( array_map('wp_setup_nav_menu_item', $menu_items), 0, (object) array('walker' => $walker ) );
 		$result .= ' </ul> ';
 		return $result;
-	} elseif ( is_wp_error( $menu ) ) {
-		return $menu;
 	}
-
-
 }
 
 /**
Index: wp-includes/nav-menu.php
===================================================================
--- wp-includes/nav-menu.php	(revision 18318)
+++ wp-includes/nav-menu.php	(working copy)
@@ -22,17 +22,17 @@
 	if ( ! $menu )
 		return false;
 
-	$menu_obj = get_term( $menu, 'nav_menu' );
+	$menu_obj = false;
 
+	if ( is_numeric( $menu ) )
+		$menu_obj = get_term( intval( $menu ), 'nav_menu' );
+
 	if ( ! $menu_obj )
 		$menu_obj = get_term_by( 'slug', $menu, 'nav_menu' );
 
 	if ( ! $menu_obj )
 		$menu_obj = get_term_by( 'name', $menu, 'nav_menu' );
 
-	if ( ! $menu_obj )
-		$menu_obj = false;
-
 	return $menu_obj;
 }