Thanks Dan. It does seem to be browser related. The problem appears in Firefox but not IE.
>If you're good with JavaScript, you can see if you can figure it out. The routines for the popup window are in the >PopupWindow.js file in the /templates/admin/English/ directory.
I am not good with JavaScript but, properly backed-up, I am a fearless hack!

I will give a try and post anything useful here.
Jason