[BlueOnyx:09990] 500 error encountered on Joomla sites after weekend updates

[Adam Lepp]

On Joomla-based sites on one of my servers, I'm getting a 500 Internal
Server error, presumably since the recent updates.

Error_log shows:  
[Mon Apr 02 12:58:50 2012] [alert] [client AA.BB.CC.DD]
/home/.sites/XX/siteYY/web/.htaccess: RewriteEngine not allowed here

It worked fine before.  This server uses Joomla v1.6.3 from Compass.
The .htaccess file is the standard one installed with Joomla (pasted below).
Everything else works fine.
Restarting httpd doesn't help. I haven't tried changing the "RewriteEngine
On" line, as I'd rather hear from fellow experts first.

Any assistance would be appreciated.
Thanks!
Adam

-----------------------------------------------

##
# @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 /j


########## 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
----------------------------------------------------------------------------
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