Sys.Application.add_load(ApplicationLoadHandler);

    function ApplicationLoadHandler(sender, args) {
        var prm = Sys.WebForms.PageRequestManager.getInstance();
        if (!prm.get_isInAsyncPostBack()) {
            prm.add_initializeRequest(initRequest);
            prm.add_endRequest(endRequest);
        }
    }
    function initRequest(sender, args) {
        var pop = $find("modpopUpdateProg");
        pop.show();
    }

    function endRequest(sender, args) {
        var pop = $find("modpopUpdateProg");
        pop.hide();
    }