AW.HTTP.Request not working in IE 5.5

I have unfortunate task of supporting a customer that is stuck with a large installed base of Windows 2000 Professional machines running Internet Explorer 5.5.
The AW.HTTP.Request that I put together for the grid works on IE 6 and 7, but not IE 5.5. The machine does have MSXML2 installed, its part of IE 5.5.

The function that I am using looks like this, it calls an ISAPI dll.

obj.onCellValidated = function(text, column, row){

var r = new AW.HTTP.Request;
r.setURL("tmtrack.dll?scriptpage");
r.setRequestMethod("POST");
r.setParameter("scriptname", "postCellUpdatePrinter");
r.setParameter("column", column);
r.setParameter("row", row);
r.setParameter("text", text);
r.request();
r.response = function(data){
alert(data); // process response data
}
}

I put some debug code in and discovered that the function goes dead when r.request(); is called. I get an alert for onCellValidated8, but no alerts after that.

obj.onCellValidated = function(text, column, row){
alert('onCellValidated');
var r = new AW.HTTP.Request;
alert('onCellValidated1');
r.setURL("tmtrack.dll?scriptpage");
alert('onCellValidated2');
r.setRequestMethod("POST");
alert('onCellValidated3');
r.setParameter("scriptname", "postCellUpdatePrinter");
alert('onCellValidated5');
r.setParameter("column", column);
alert('onCellValidated6');
r.setParameter("row", row);
alert('onCellValidated7');
r.setParameter("text", text);
alert('onCellValidated8');
r.request();
alert('onCellValidated9');
r.response = function(data){
alert(data); // process response data
}
alert('onCellValidated10');
}

It might be that the XMLHttpRequest ActiveX is registered there under different ID (not MSXML2.XMLHTTP) - try adding several of them -

if (AW.ie) {
    AW.createXMLHttpRequest = function(){
        var i, a = ["MSXML2.XMLHTTP", "Microsoft.XMLHTTP", "MSXML2.XMLHTTP.4.0"];
        for (i=0; i<a.length;i++){
            try {
                var x = new ActiveXObject(a[i]);
                if (x) {
                    return x;
                }
            }
            catch(err){
            }
        }
        alert("Cannot create XMLHTTPRequest ActiveX control");
    };
}