Href Name Tags Not Working In Firefox?

I'm pretty sure this is a Javascript issue, despite the subject line of this message.I'm using Javascript to create a popup window on my site. Users click on the link and get a popup with supplemental information about the item they clicked on. Works great. The html link to open the popup looks like this:

<a href="javascript:popup(xMoreInfo_popup)" onMouseOut="clearEl();">Click HERE for more information</a>

...where "xMoreInfo_popup" is a variable that tells the "popup" function which information (html code) to display. This then connects to a Javascript function that looks like this:

var popupWin
var wholeWin
function popup(term) // write corresponding content to the popup window

[code]....

Now to my problem. This works as expected and just perfectly in IE. If the user clicks on the GO TO SUPPLEMENTAL link, it autoscrolls down to the supplemental information. In Firefox, however, it behaves quite oddly. Instead, when the link is clicked, the popup window displays the html from the original parent, rather than the information in the popup window! Now I can click on the original "parent window" link in the popup window, then it shows the popup information again in the same popup window, but autoscrolled to the proper place this time.