Widget is displaying a fatal error and breaking my theme. I went to the website for this plugin and I see the same error in your sidebar (widget) as well:
Fatal error: Cannot use object of type WP_Error as array in /home/username/public_html/wp-content/plugins/simply-instagram/simply-instagram-functions.php on line 187
WP is 3.5.1, multi-site
Genesis child theme.