Error You don't have permission to access /index2.  

Hola, buenas a todos

Estoy montando una tienda online con joomla y virtuemart, al intentar realizar modificaciones en el apartado Virtuemart-Editar Tienda, el servidor me da el siguiente mensaje de error:

Forbidden

You don't have permission to access /index2.php on this server.

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

El usuario que realiza las modificaciones tienes permisos de administrador y puede publicar artículos, modificar los existentes...

He probado a añadir al .htacces las siguientes lineas:
########## Attempt to solve 'Global Configuration' save issue, FTP layer issue, Media Upload issue
SecFilterEngine Off
SecFilterScanPOST Off
########## End - Attempt to solve 'Global Configuration' save issue, FTP layer issue, Media Upload issue
Pero entonces da este error:
Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, webmaster@sidecolor.es and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.
Porque no está instalado el modulo mod_security.

¿Alguna idea de como solucionarlo?, cualquier aporte sera bienvenido, gracias.