title: jQuery Ajax returning 404 Error, but correct Response
body: <p>I'm posting some data to a PHP script via jQuery AJAX, and everything executes correctly, but it returns a 404 error.  In my Firebug console the response from the PHP script is correct.  I don't understand how the script can respond, and it is still throwing a 404 error.  The jQuery "error" callback method triggers, and the "success" method doesn't.</p>
  
  <p>All statements performed by the PHP script work accurately, because I can see the database being updated, etc.</p>
  
  <p>I'm using jQuery 1.4.2, on a WordPress 3.x website hosted by Dreamhost.</p>
  
  <p><strong>-----------MORE INFO-----------</strong></p>
  
  <p>OK, I've figured out that when I include WordPress's <code>wp-blog-header.php</code> file in the Ajax script, I get the error. Also, once upon a time these scripts work, and I am 90% sure they stopped working after the WP 3.0 update.  I'll paste in the Response headers from Firebug.</p>
  
  <p><strong>This header response from PHP that includes the wp-blog-header.php and returns a 404 error in Firebug...</strong></p>
  
  <pre><code>Date                Tue, 10 Aug 2010 01:44:44 GMT
  Server            Apache
  X-Powered-By        PHP/5.2.6
  X-Pingback        http://www.learnwake.com/xmlrpc.php
  Expires          Wed, 11 Jan 1984 05:00:00 GMT
  Cache-Control       no-cache, must-revalidate, max-age=0
  Pragma            no-cache
  Last-Modified       Tue, 10 Aug 2010 01:44:44 GMT
  Vary                Accept-Encoding
  Content-Encoding    gzip
  Content-Length    36
  Keep-Alive        timeout=2, max=98
  Connection        Keep-Alive
  Content-Type        text/html; charset=UTF-8
  </code></pre>
  
  <p><strong>This header response from PHP that doesn't include the wp-blog-header.php and returns a 200 OK in Firebug...</strong></p>
  
  <pre><code>Date                Tue, 10 Aug 2010 01:44:58 GMT
  Server            Apache
  X-Powered-By        PHP/5.2.6
  Vary                Accept-Encoding
  Content-Encoding    gzip
  Content-Length    36
  Keep-Alive        timeout=2, max=100
  Connection        Keep-Alive
  Content-Type        text/html
  </code></pre>