Fai una prova cosi:

codice:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3.org/TR/html4/frameset.dtd">
<html>
<head>
<title>prova </title>
<script language="JavaScript" type="text/javascript">
<!--
function change2()
{//ho provato tutti questi modi ma niente
parent.sponsor.location="12frame.htm";
parent.frames[1].location="12frame.htm";
parent.sponsor.location.src="12frame.htm";
parent.sponsor.location.hrif="12frame.htm";
}
//-->
</script>

</head>

<frameset cols='120, *'>

 <frame name='menu' src="timer.php" scrolling='auto'>

<frameset rows='333,405' cols='*'>
<frame name='sponsor' src="timer.php" scrolling='auto'>

<frame name='homepage1' src="timer.php" scrolling='auto'>


</frameset>
<noframes><body>"


spiacente il tuo browser non supporta i frames</p>
</body></noframes>
</frameset>
<script LANGUAGE="JavaScript"  type='text/javascript'>setInterval("change2()",5000);</script>


</html>
5000 è il timeout in formato millisecondi