I use joomla 1.0.13 and artio sef 2.1.0. After installed the artio sef, and config the .htaccess file like the instruction, I got this:

403 Forbidden
You don't have permission to access /index.php on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

How can i fix this? please help!!!