Opening popUp Window in IE5

[jtsmk]

I'm having problems opening a popUp window (pointing to an html page) in IE5.
Here is the javascript call I used which worked in IE4.x:
<A HREF="myPage.htm" target="newWin" onClick="popUp()">Link</A>

I next tried this call: <A HREF="javascript:popUp()">Link</A>
which workk fine in NAV but not IE5.

For the function I used:
function popUp()
{
x = open('', 'newWin', 'width=800, height=600, resizable, scrollbars');
x.document.open();
}

where I substituted the URL for the null argument for my second call.

I'm not sure if this is an IE5 bug or what. Any help would be appreciated.