Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);
Sys.WebForms.PageRequestManager.getInstance().add_beginRequest(disableControls);

$("#SIFForm1C input, #SIFForm1C a").attr('disabled', true);

function disableControls(sender, args) {
    // Disable input controls on the SIF Form
    $("#SIFForm1C input").attr('disabled', true);
    $("#SIFForm1C a").hide();
}

function EndRequestHandler(sender, args) {
    // Re-enable input controls on the SIF Form
    $("#SIFForm1C input").attr('disabled', false);
    $("#SIFForm1C a").show();
}