Hmmm... not working on Netscape is probably not much of a problem... but
if you want to sort it out so Netscape Users don't get the problem - you could use ASPX Master Files to direct at PreInit which page people go to according to their browser - asking Netscape users to use Internet Explorer if they want to use the page, and showing Internet Explorer Users the page anyway.
This is... Flash Code? I'm not sure how to fix it - I don't know much about Flash. It could just be a Netscape problem.