Menu page note displaying and recieving a fatal error message
Catchable fatal error: Object of class WP_Error could not be converted to string in /u/k/ksze/www.liondancetoronto.com/wp-includes/formatting.php on line 511
That error is from the WordPress core and is not part of the theme. I would suggest first deactivating the theme file and moving to one of the default WordPress themes (twentythirteen for example).
Then deactivate any plugins you have active and trying to view the menus manager again.
If you are still having issues make sure your WordPress is up to date and on 3.6. If you are still having issues you will need to re-install WordPress.