Netscape Communicator 4.75.
The first time I did it, I saw what you were talking about. Since your side menu is an image map, my suspicion was that something on the reload was causing the script to end before the image map (that you output at the bottom of the page source) could be output so it was not getting to the browser.
When I went back through the sequence again, it started working, so I couldn't verify my theory with the view-source command.
I would suggest that you check the resulting html with a syntax checker of some kind. My experience has been that whenever someone says "it is only broken in Netscape" the problem is usually non-standards compliant html. Netscape 4.x is much stricter than IE. IE will usually tolerate html errors where Netscape will not.
-- Rich Rijnders
-- Irvine, CA US