title: jQuery AJAX and IE8 outputs "Invalid argument"
body: <p>guys!
  It is very strange thing. This code normally works in all browsers I know, except IE8 (may be IE7 too).</p>
  
  <pre><code>function xajax_xfrmproc(sender, eventname, data, formname, data2) {
  
  var dt = {};
  dt.__xr = 1;            // AJAX request flag
  dt.__sender = sender;
  dt.__eventname = eventname;
  dt.__data = data;
  dt.__formname = formname;
  dt.__data2 = data2;
  
  $.ajax({
      type: 'POST',
      url: '',
      data: dt,
      error: function(req, text, error) {
          alert('AJAX Error: ' + text + ' | ' + error + ':' + "\n" + req.responseText);
      },
      success: function (json) {
          jxr_decode(json);
      },
      dataType: "json"
  });
  }
  </code></pre>
  
  <p>It calls error method and writes: "AJAX Error: error | Error: Invalid argument".</p>
  
  <p>You can test is online here: <a href="http://stat.8-800.su" rel="nofollow">http://stat.8-800.su</a> (enter any values and press "Войти в статистику" button).</p>
  
  <p>I check in over all internet but not found anything useful.
  I've tried to set AddDefaultCharset utf-8, nothing happens.</p>