title: jQuery AJAX requests failing in IE8 with message 'Error: This method cannot be called until the open method has been called.'
body: <p>I'm using jQuery 1.4.2 and am trying to perform a simple AJAX request.  The target URL returns a JSON string (I validated it with jslint).  The request works in Firefox and Chrome, but doesn't want to work in IE8, and I can't determine why.  Here is the call:</p>
  
  <pre><code>jQuery.ajax({
  url: 'http://' + domain + '/' + 'helper/echo/',
  dataType: 'json',
  success: function(data) {
   alert(data);
  },
  beforeSend: function(request, settings) {
   alert('Beginning ' + settings.dataType + ' request: ' + settings.url);
  },
  complete: function(request, status) {
   alert('Request complete: ' + status);
  },
  error: function(request, status, error) {
   alert(error);
  }
  });
  </code></pre>
  
  <p>IE will execute the beforeSend callback and the error callback.  The error callback alerts with the message:</p>
  
  <pre><code>Error: This method cannot be called until the open method has been called.
  </code></pre>
  
  <p>My response header returns with <code>Content-Type: text/javascript; charset=UTF-8</code>.</p>
  
  <p>What is going on with IE?  I'm running the server on localhost, making a request from <a href="http://localhost:8080/psx">http://localhost:8080/psx</a> to <a href="http://localhost:8080/helper">http://localhost:8080/helper</a>.  Maybe IE is blocking this request?  I have tried installing Fiddler to analyze request traffic but it won't run on my machine because it's rather locked down.  Firebug lets me, but everything seems good there.</p>
  
  <p>Thanks for the help!!!</p>