var mymessage = "Sorry, rightclick has protected on this Page.";
function rtclickcheck(keyp)
{
  if (navigator.appName == "Netscape" && keyp.which == 3)
  {
    alert(mymessage);
    return false;
  }
  if (navigator.appVersion.indexOf("MSIE") != -1 && event.button == 2)
  {
    alert(mymessage);
    return false;
  }
}
document.onmousedown = rtclickcheck