Sys.WebForms.PageRequestManager.getInstance().add_beginRequest(beginReq);
Sys.WebForms.PageRequestManager.getInstance().add_endRequest(endReq);

function beginReq(sender, args) {
////	// shows the Popup 
	////	$find(ModalProgress).show();
 if (typeof(ModalProgress) === 'string') {   
   var pop = $find(ModalProgress);   
 
    pop.show();   
 }   

}

function endReq(sender, args) {
//////	//  shows the Popup 
	//////	$find(ModalProgress).hide();

	if (typeof (ModalProgress) === 'string') {
		var pop = $find(ModalProgress);

		pop.hide();
	}  
}