Hi Kevin, I fixed it for you.
Apparently when we auto-upgraded your site to WP 3.5.1, the permissions got set wrong on your webfolder, so I changed it to the correct one (755) and voila!
In the debugging, I noticed you had WP Super Cache enabled, but the .htaccess and wp-config.php files didn't have any of the settings in there, so that was causing the error to be kinda cached. I turned off the plugin, but you can reactivate it as needed
Don't forget to update your themes and plugins!