function CheckPopUp(){
 if (typeof PopUpWin == "object"){
  if (!PopUpWin.closed){
   PopUpWin.close();
  }
 }
}

function show(page){ 
  CheckPopUp();
  PopUpWin = window.open(page,"Zoom","height=360,width=340,dependent=yes,resizable=no,statusbar=no");
}