Clean URL's turn 404's into 500's - Reporting the Solution

We have spent much time tracking this problem down, found a solution, and from what I see doing searches it affects many people with many hosting providers.

We had to initially comment out the .htaccess rules that make Clean URL's work. The solution to getting Clean URL's to work and not turning 404's into 500's is as follows:

Add the line:

  #Added to keep from getting 500 errors at 1&1 w/ Clean URLs enabled
  RewriteBase /

Just after:
RewriteEngine on

to the .htaccess file in the web root. I will paste in more of the file so that you clearly see the proper context for this addition.

Maybe you would take a look at this and consider the change for the next update to Drupal.

Thanks!
Michael

# Various rewrite rules.
<IfModule mod_rewrite.c>
  RewriteEngine on

  #Added to keep from getting 500 errors at 1&1 w/ Clean URLs enabled
  RewriteBase /

  # If your site can be accessed both with and without the 'www.' prefix, you
  # can use one of the following settings to redirect users to your preferred
  # URL, either WITH or WITHOUT the 'www.' prefix. Choose ONLY one option:
  #
  # To redirect all users to access the site WITH the 'www.' prefix,
  # (http://example.com/... will be redirected to http://www.example.com/...)
  # adapt and uncomment the following:
  # RewriteCond %{HTTP_HOST} ^example\.com$ [NC]
  # RewriteRule ^(.*)$ http://www.example.com/$1 [L,R=301]