Erreur 404 et htaccess

Bonjour,
Vous trouverez ci-dessous mon fichier HTACCESS ou il y a apparemment un souci qui me donne des erreurs 404 avec des URLS bizarres ou le nom de domaine se répète deux fois ex: http:/www.monsite.com/http:/www.monsite.com
ou http:/www.monsite.com/contact.html/http:/www.monsite.com/contact.html
Mon site est sous joomla 1.5 avec sh404 sef
NB: j'ai un autre site garé www.monsite2.com qui pointe vers le site principale, est e que possible que le problème provient du site garé ? parce que si on clique su n'importe quel lien depuis le site www.monsite2.com j'ai l'erreur 404 avec le double URLS.

Merci pour votre aide

##
# @version $Id: htaccess.txt 5973 2006-12-11 01:26:33Z robs $
# @package Joomla
# @copyright Copyright (C) 2005 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.
#
# Only use one of the two SEF sections that follow.  Lines that can be uncommented
# (and thus used) have only one #.  Lines with two #'s should not be uncommented
# In the section that you don't use, all lines should start with #
#
# For Standard SEF, use the standard SEF section.  You can comment out
# all of the RewriteCond lines and reduce your server's load if you
# don't have directories in your root named 'component' or 'content'
#
# If you are using a 3rd Party SEF or the Core SEF solution
# uncomment all of the lines in the '3rd Party or Core SEF' section
#
#####################################################

#####  SOLVING PROBLEMS WITH COMPONENT URL's that don't work #####
# SPECIAL NOTE FOR SMF USERS WHEN SMF IS INTEGRATED AND BRIDGED
# OR ANY SITUATION WHERE A COMPONENT's URL's AREN't WORKING
#
# In both the 'Standard SEF', and '3rd Party or Core SEF' sections the line:
# RewriteCond %{REQUEST_URI} ^(/component/option,com) [NC,OR] ##optional - see notes##
# May need to be uncommented.  If you are running your Joomla!/Mambo from
# a subdirectory the name of the subdirectory will need to be inserted into this
# line.  For example, if your Joomla!/Mambo is in a subdirectory called '/test/',
# change this:
# RewriteCond %{REQUEST_URI} ^(/component/option,com) [NC,OR] ##optional - see notes##
# to this:
# RewriteCond %{REQUEST_URI} ^(/test/component/option,com) [NC,OR] ##optional - see notes##
#
#####################################################

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

#
#  mod_rewrite in use

RewriteEngine On
RewriteCond %{HTTP_HOST} ^sarah-shuttle.com$ [OR]
RewriteCond %{HTTP_HOST} ^sarah\-shuttle\.com$ [OR]
RewriteCond %{HTTP_HOST} ^www\.sarah\-shuttle\.com$
RewriteRule ^/?$ "http\:\/\/www\.paris\-shuttle\-airport\.com\/" [R=301,L]

#  Uncomment following line if your webserver's URL
#  is not directly related to physical file paths.
#  Update Your Joomla!/MamboDirectory (just / for root)

# RewriteBase /

########## Begin - Joomla! core SEF Section
############# Use this section if using ONLY Joomla! core SEF
## ALL (RewriteCond) lines in this section are only required if you actually
## have directories named 'content' or 'component' on your server
## If you do not have directories with these names, comment them out.
#
#RewriteCond %{REQUEST_FILENAME} !-f
#RewriteCond %{REQUEST_FILENAME} !-d
#RewriteCond %{REQUEST_URI} ^(/component/option,com) [NC,OR] ##optional - see notes##
#RewriteCond %{REQUEST_URI} (/|\.htm|\.php|\.html|/[^.]*)$ [NC]
#RewriteRule ^(content/|component/) index.php
#
########## End - Joomla! core SEF Section

########## Begin - 3rd Party SEF Section
############# Use this section if you are using a 3rd party (Non Joomla! core) SEF extension - e.g. OpenSEF, 404_SEF, 404SEFx, SEF Advance, etc
#
RewriteCond %{REQUEST_URI} ^(/component/option,com) [NC,OR] ##optional - see notes##
RewriteCond %{REQUEST_URI} (/|\.htm|\.php|\.html|/[^.]*)$ [NC]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule (.*) index.php
#
########## End - 3rd Party SEF Section

########## 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 <script> tag in URL
RewriteCond %{QUERY_STRING} (\<|%3C).*script.*(\>|%3E) [NC,OR]
# Block out any script trying to set a PHP GLOBALS variable via URL
RewriteCond %{QUERY_STRING} GLOBALS(=|\[|\%[0-9A-Z]{0,2}) [OR]
# Block out any script trying to modify a _REQUEST variable via URL
RewriteCond %{QUERY_STRING} _REQUEST(=|\[|\%[0-9A-Z]{0,2})
# Send all blocked request to homepage with 403 Forbidden error!
RewriteRule ^(.*)$ index.php [F,L]
#
########## End - Rewrite rules to block out some common exploits

########## BEGIN Cache-Control Headers
<IfModule mod_headers.c>
 <FilesMatch "\\.(ico|jpe?g|png|gif|swf|css|gz)$">
 Header set Cache-Control "max-age=2592000, public"
 </FilesMatch>
 <FilesMatch "\\.(js)$">
 Header set Cache-Control "max-age=2592000, private"
 </FilesMatch>
<filesMatch "\\.(html|htm)$">
Header set Cache-Control "max-age=7200, public"
</filesMatch>
# Disable caching for scripts and other dynamic files
<FilesMatch "\.(pl|php|cgi|spl|scgi|fcgi)$">
Header unset Cache-Control
</FilesMatch>
</IfModule>
########## END Cache-Control Headers

########## Begin - Remove Etags
#
FileETag none
#
########## End - Remove Etags

#Begin Expire headers
<IfModule mod_expires.c>
 ExpiresActive On
 ExpiresDefault "access plus 7200 seconds"
 ExpiresByType image/jpg "access plus 2592000 seconds"
 ExpiresByType image/jpeg "access plus 2592000 seconds"
 ExpiresByType image/png "access plus 2592000 seconds"
 ExpiresByType image/gif "access plus 2592000 seconds"
 AddType image/x-icon .ico
 ExpiresByType image/ico "access plus 2592000 seconds"
 ExpiresByType image/icon "access plus 2592000 seconds"
 ExpiresByType image/x-icon "access plus 2592000 seconds"
 ExpiresByType text/css "access plus 2592000 seconds"
 ExpiresByType text/javascript "access plus 2592000 seconds"
 ExpiresByType text/html "access plus 7200 seconds"
 ExpiresByType application/xhtml+xml "access plus 7200 seconds"
 ExpiresByType application/javascript A259200
 ExpiresByType application/x-javascript "access plus 2592000 seconds"
 ExpiresByType application/x-shockwave-flash "access plus 2592000 seconds"
</IfModule>
# END Expire headers