Shoutbox

You should only use the responseText property when (xmlhttp.readyState == 4) and (xmlhttp.status == 200). Try that and see if it works.

code:

---

(...)
xmlhttp.onreadystatechange = function () {
   if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
         // Data is available now
         DoSomethingUseful(xmlhttp.responseText);
      }
   }
}
xmlhttp.send();

---

And forget about while loops for doing that. Seriously. Forget it.