htaccess RewriteCond changed to RRewriteCond

Once a week (usually on weekends) the htaccess file in my blog is changed from:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress

to

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RRewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress

Note the first RewriteCond becomes RRewriteCond.

I am running WP 2.9.2 w/ LAMP. I have the following plugins:

Akismet
BulletProof Security
Clean WP Dashboard
Collision Testimonials
Contact Form 7
Disable Theme Preview
Disable WordPress Core Update
Disable WordPress Plugin Updates
FAQ You
Google XML Sitemaps
Hide Admin Panels
ILC Folding
IMM-Glossary
MaxBlogPress Ping Optimizer
MEE News
MiniMeta Widget
Optimize DB
Page Link Manager
Ping List Checker
Ping.fm
Quotes Collection
Reveal IDs for WP Admin
SB Child List
Search Meter
Secure WordPress
Simple Feed Copyright
Static Front Page
StatPress Reloaded
tags4page
The Events Calendar
WordPress Database Backup
WP Security Scan
WP Shopping Cart
WP Title 2
WP-phpMyAdmin

I did a code search through the plugins for “RRewriteCond” but found nothing. I’m not surprised because I have other sites that use the same plugin set, and they don’t have this problem.

Another site suggested checking privileges for the htaccess file – they are set at 644.

Because the server returns and error if there are any bad instructions in htaccess, I usually start my week with my site offline with Internal Server Error 500.

As soon as I FTP to the site and delete .htaccess, it works fine again for another week. Server logs don’t show anything (or I’m looking for the wrong thing).

Suggestions please.