I really wouldn't waste any time on IE6 since Microsoft has a campaign going eliminate it
. If the site works in ie8, safari, firefox and chrome and not in IE6 i would say the site works.
However if you want to dig into it. I'd suggest you view the page and then the source and copy the source to a text document, call it femie6.html
Now you can open this file in your browser and start taking things out to see if you can get it to work., strip it down to the essentials, remove unused CSS, scripts, html. Do a little at a time and you might find a solution.