instalacion de sh404sef

hola fijense que instale el componente sh404sef active las url amigables y active el modo rewrite cont

en un articulo que hay aqui dice que ya no tengo que añadirle nada al archivo .htacces

es componente lo he instalado en joomla 1.0 y lo instalo bien

pero aqui en la version 1.5 me da un problema que hago todo y lo activo el componente pero cuando entor a las paginas o opciones del menu todo meda error 404

les dejo el link de miweb http://www.tabascomio.com/web/
veran la pagina principal bien, pero denle a cualquier opcion y manda error 404

si alguien me puede orientar para resolver este problema, se lo agradecere mucho, esto es lo que contiene mi archivo .htacces

##
# @version $Id: htaccess.txt 10492 2008-07-02 06:38:28Z ircmaxell $
# @package Joomla
# @copyright Copyright (C) 2005 – 2008 Open Source Matters. All rights reserved.
# @license http://www.gnu.org/copyleft/gpl.html GNU/GPL
# Joomla! is Free Software
##

#####################################################
# READ THIS COMPLETELY IF YOU CHOOSE TO USE THIS FILE
#
# The line just below this section: ‘Options +FollowSymLinks’ may cause problems
# with some server configurations. It is required for use of mod_rewrite, but may already
# be set by your server administrator in a way that dissallows changing it in
# your .htaccess file. If using it causes your server to error out, comment it out (add # to
# beginning of line), reload your site in your browser and test your sef url’s. If they work,
# it has been set by your server administrator and you do not need it set here.
#
#####################################################

## Can be commented out if causes errors, see notes above.
Options +FollowSymLinks

#
# mod_rewrite in use

RewriteEngine On

########## Begin – Rewrite rules to block out some common exploits
## If you experience problems on your site block out the operations listed below
## This attempts to block the most common type of exploit `attempts` to Joomla!
#
# Block out any script trying to set a mosConfig value through the URL
RewriteCond %{QUERY_STRING} mosConfig_[a-zA-Z_]{1,21}(=|%3D) [OR]
# Block out any script trying to base64_encode crap to send via URL
RewriteCond %{QUERY_STRING} base64_encode.*(.*) [OR]
# Block out any script that includes a