You should have posted your script code so we could have pointed out the problem more easily.
However I am going to take a guess that your code doesn't check to see which browser it is running on. The problem is that the event object is not standard across browsers and the way to access the key being pressed is different, look at this example and see if it helps
[html]
<html>
<body>
<script type="text/javascript">
function noNumbers(e)
{
var keynum
var keychar
var numcheck
if(window.event) // IE
{
keynum = e.keyCode
}
else if(e.which) // Netscape/Firefox/Opera
{
keynum = e.which
}
keychar = String.fromCharCode(keynum)
numcheck = /\d/
return !numcheck.test(keychar)
}
</script>
<form>
<input type="text" onkeypress="return noNumbers(event)" />
</form>
</html>
[/html]
This example comes from
http://www.w3schools.com/jsref/jsref_onkeypress.asp 
4
