IE 5.2 on Mac platforms does have problems with MIME-type handling on occasion, perhaps you're falling into one of those.

I had several users complain when I updated a shop to serve an XHTML 1.1 compliant template, because Mac IE 5.2.3 chokes on it and serves up the error above.

I used the the article at http://juicystudio.com/article/content-negotiation.php to verify the issue & then http://httpd.apache.org/docs/2.2/con...gotiation.html to configure the mod_negotiation module to serve pages to HTTP 1.0 browsers (MacIE, Lynx, etc) as straight HTML.