Ello,
I havent tested this script as yet but one thing i know is that Netscape has a bug which means any calls for javascript libarys needs to be placed directly under the body tag. I have had the same problem.
Try......
<body bgcolor="#FFFFFF" onload="WM_initialize_toolbar()">
<script language="javascript" src="menufunctions2.js"></script>
<div id="container" style="position: absolute; left: 50px; top:50px; width:150px; height: 400px; visibility: hidden;;
etc.....