Попробуйте оставить внутри .htaccess, только эти строки:
<IfModule mod_rewrite.c>
    RewriteEngine On
    #RewriteBase /
   
    RewriteRule ^(robots.txt)$ $1 [L]

    RewriteCond %{HTTP:Authorization} ^Basic.*
    RewriteRule ^(.*)$ index.php?http_authorization=%{HTTP:Authorization} [QSA,L]   
   
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteRule ^(.*)$ index.php [QSA,L]
</IfModule>

#Запрещаем открывать файлы напрямую
<Files ~ "(\.inc\.php|\.tpl|\.tpl\.php|\.auto\.php)$">
    Order allow,deny
    Deny from all
</Files>

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

Please contact the server administrator, admin@example.com 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.

Apache/2.2.22 (Win32) mod_ssl/2.2.22 OpenSSL/1.0.1c PHP/5.3.13 Server at test1.ru Port 80"