function ajaxStart()
    {
      var xmlHttp;
      try
      {
          // Firefox, Opera 8.0+, Safari
          xmlHttp=new XMLHttpRequest();
      }
      catch (e)
      {
          // Internet Explorer
          try
          {
              xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
          }
          catch (e)
          {
              try
              {
                  xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
              }
              catch (e)
              {
                  alert("Your browser does not support AJAX!");
                  return false;
              }
          }
      }

      return xmlHttp;
  }