i think this can be done in much simpler manner without Postback
see here is the demo
Page 1:Disable.htm
<html>
<head>
<title></title>
<script>
function Disable(controleid) {
document.getElementById(controleid.id).disabled = true;
window.open("Enable.htm");
}
</script>
</head>
<body >
<input type="button" id="one" onclick="Disable(this)" />
</body>
</html>
Page 2:Enable.htm
<html>
<head>
<title></title>
<script>
function Enabled() {
window.top.opener.document.getElementById('one').disabled = false;
}
</script>
</head>
<body >
<input type="button" id="two" onclick="Enabled()" />
</body>
</html>