var pbControl = null;

if (Sys.WebForms.PageRequestManager != null) {

    var prm = Sys.WebForms.PageRequestManager.getInstance();

    prm.add_beginRequest(BeginRequestHandler);
    function BeginRequestHandler(sender, args) {
        pbControl = args.get_postBackElement();
        pbControl.disabled = true;
        document.body.style.cursor = "wait";
    }

    prm.add_endRequest(EndRequestHandler);
    function EndRequestHandler(sender, args) {
        pbControl.disabled = false;
        pbControl = null;
        document.body.style.cursor = "default";

        if (args.get_error() != undefined) {
            if (args.get_error().message.substring(0, 51) == "Sys.WebForms.PageRequestManagerParserErrorException") {
                window.location.reload();
            }
            args.set_errorHandled(true);
        }
    }
}