IE 5.0 vs IE 5.5 -- Re: onClick & Checkboxes

the code below will work fine when viewed with IE5.0 but will not work at all under 5.5. Why? What can I do to correct this? I have been working for a whild on a very large (and complex) project, when I was done I took it to my boss' desk to have it not work (I was usning IE 5.0 and he had 5.5. I have narrowed it down to this problem. The onClick will not get to the function. if I replace the function call with an alert it will fire but not go to the function the way I need :(.
Thanks in advance,
Michael

<HTML>
<HEAD>
<TITLE> New Document </TITLE>
<SCRIPT LANGUAGE="JavaScript">
function hasFocus(){
alert("got here");
}
</script>
</HEAD>
<BODY>
<input type="checkbox" name="CHK" value="1" onClick="hasFocus()">
</BODY>
</HTML>

<HTML>
<HEAD>
<SCRIPT LANGUAGE="JavaScript">
function CHK_onclick(){
alert("got here");
}
</script>
</HEAD>
<BODY>
<input type="checkbox" name="CHK" value="1" onClick="return CHK_onclick()">
</BODY>
</HTML>

Thanks! yesterday I was angry with a certian browser's creators but now I just feel silly since I chose a poor name for a function :)
Thanks again,
Michael