Apache must be configured to allow the modules above. If you receive a "500 internal error" when serving requests to anonymous users you need to dig into your Apache configuration. This configuration in my virtual host works for me:
<Directory /home/www/> AllowOverride All </Directory>
Basicamente es que pruebes poniendo la linea <Dire.... ry> en tu .htaccess
fuente:
http://wordpress.org/plugins/wp-supe.../installation/