I’ve got the same error. When on admin panel I clic on “Appearence>Menus” this error is displayed :
Catchable fatal error: Object of class WP_Error could not be converted to string in /home/studxzg/public_html/projets/reyvok/wordpress/wp-includes/formatting.php on line 446
I have this problem since I upgraded WordPress from 3.1 to 3.1.1
