var nav = window.Event ? true : false;
if (nav) {
   window.captureEvents(Event.KEYDOWN);
   window.onkeydown = NetscapeEventHandler_KeyDown;
} else {
   document.onkeydown = MicrosoftEventHandler_KeyDown;
}

function NetscapeEventHandler_KeyDown(e) {  
  if (e.which == 13 && e.target.type != 'textarea' && e.target.type != 'submit') 
  { 
    __doPostBack(defaultButtonID,'');
  }
  return true;
}

function MicrosoftEventHandler_KeyDown() {
  if (event.keyCode == 13 && event.srcElement.type != 'textarea' && event.srcElement.type != 'submit'){
    __doPostBack(defaultButtonID,'');
	return false;
  }
  return true;
}