errore 500 :(

Ciao a tutti,
da qualche tempo il mio sito continua a dare errore 500 ed è praticamente impossibile da visitare.
Non ho apportato nessuna particolare modifica. Ho letto che potrebbe esseere un problema di dimensione del sito? che in effetti inizia ad essere un po' voluminoso.
L'indirizzo è: http://cart3.altervista.org
Basta fare qualche clic e... l'errore arriva. Su qualsiasi pagina, compresa la home.
Il file .htttacces mi sembra a posto, in base a quello che ho letto:

# # av:php5-engine
AddHandler av-php53 .php

##
# @version $Id: htaccess.txt 14401 2010-01-26 14:10:00Z louis $
# @package Joomla
# @copyright Copyright (C) 2005 - 2010 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!
#
## Deny access to extension xml files (uncomment out to activate)
#<Files ~ "\.xml$">
#Order allow,deny
#Deny from all
#Satisfy all
#</Files>
## End of deny access to extension xml files
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

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

RewriteBase /


########## Begin - Joomla! core SEF Section
#
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} !^/index.php
RewriteCond %{REQUEST_URI} (/|\.php|\.html|\.htm|\.feed|\.pdf|\.raw|/[^.]*)$ [NC]
RewriteRule (.*) index.php
RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization},L]
#
########## End - Joomla! core SEF Section

Però c'è anche un altro .httacess.txt mentre quello di prima non ha estensione. A quale devo eventualmente riferirmi?
Joomla è aggiornato all'ultima versione: 2.5.4

Grazie per ogni aiuto!!!!
Roberto

[EmoArt]

quello con .txt eliminalo e vedi cosa succede, ad ogni modo non ti creerà problemi il toglierlo, 2 non servono

Grazie, provo.
Anche se, dopo aver postato il messaggio, il problema è per il momento scomparso.
Appena so, mi rifaccio vivo.
Ciao, grazie
Roberto