WordPress 2.9.2 crashes site w/500 internal server error

I'm helping a colleague with a recurring issue that's just started happening to multiple sites of his after upgrading to the latest release of WP... He had 4 sites go down today. Here's the message he received back from the server host...

The coding that wordpress posts into the .htaccess file is basically being re-pasted in a malformed fashion. Basically we just separate these two as you can see below. Contrary to the post statement I had seen previously, there is nothing in the apache logs files indicating any changes to you site. Neither are there entries ove开发者_如何学Gor cpanel or FTP. All methods of compromise have been exhausted. I do not believe your scripts are being compromised in any manner. This is an issue within wordpress itself. Have there been any changes to the blogs, or perhaps any changes that effected all accounts recently?

The curious part to me in the extract of contents from hit .htaccess file is this:

</IfModulden
# END Word</Limit>
AuthName siteeakers.net
AuthUserFile /home/site/public_html/_vti_pvt/service.pwd
AuthGroupFile /home/site/public_html/_vti_pvt/service.grp

Here is the full text from the hosting provider or the before and after htaccess fix...

Before...

root@cherry [/home/site/public_html]# cat .htaccess

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModulden
# END Word</Limit>
AuthName siteeakers.net
AuthUserFile /home/site/public_html/_vti_pvt/service.pwd
AuthGroupFile /home/site/public_html/_vti_pvt/service.grp
Options All -Indexes

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

# END WordPress

After...

root@cherry [/home/site/public_html]# cat .htaccess
AuthName siteeakers.net
AuthUserFile /home/site/public_html/_vti_pvt/service.pwd
AuthGroupFile /home/site/public_html/_vti_pvt/service.grp
Options All -Indexes

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

# END WordPress

This

</IfModulden
# END Word</Limit>

is definitely a replace operation gone wrong. It should probably read

</IfModule>
# END WordPress

Update: I think I found some related bugs:

• Wordpress Bug #11903

• Wordpress Bug #12324

the latter was closed as a duplicate of the former. From what I can see, the function Wordpress uses to write the .htaccess files can crash on a busy server.

11903 seems to have a patch. If this is your problem, maybe try it out.

Things like this are why you should never, ever try to update a live system. Have a local or parallel copy to try things out with; Then do a simple directory rename to replace the running versions.