html

Here is a small simple HTML Program
The problem that I am facing is that this Program can't be Refreshed usinf refresh method
Please point out the Error and also a solution to this
Program:- <html>
<head>
<script language=javascript>
function v()
{
if (!isNaN(document.all.txt1.value))
{
alert("Error")
}

}

</script>
</head>
<body >
<input type="text" name="txt1" value="">
<input type="button" name="bt1" value="hit" onClick="v()">
</body>
</html>

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I think this is really more appropriate to the "HTML and JavaScript" forum, so I've moved it.