<script type="text/javascript">

 //BUG
 var d = new Date("Mar 29 2009 01:00:00");
 alert("Old date : " + d);
 d.setHours(d.getHours() + 1);
 alert("New date : " + d); //stays same

 //OTHER DATES WORKING, eg
 var d = new Date("Mar 29 2010 01:00:00");
 alert("Old date : " + d);
 d.setHours(d.getHours() + 1);
 alert("New date : " + d); //displays +1 h

</script>