It seems that you are trying to run Kirby in a subfolder of your domain http://www.grousepartners.org/\
Please go to site/config/config.php and make sure to add the following rules:
c::set('url', 'http://www.grousepartners.org/\');
… and …
c::set('subfolder', '\');
You might also need to adjust your .htaccess file if you are using mod_rewrite
RewriteBase /\
Read more about it in the Kirby Docs: http://getkirby.com/docs