[david_kw]

Try this in your handler to see if the browser is getting any return and what kind.

http.onreadystatechange = function() {//Call a function when the state changes.
  if (http.readyState == 4) {
    alert("status = '" + http.status + "'");
    alert("response = '" + http.responseText + "'");
    if (http.status == 200) {
      showComments();
    }
  }
}

That should find out if the problem is in the post or the get portion of the code.

david_kw