I take it you are using NTFS authorization, not DMS...have you tried unchecking 'Enable Anonymous access' and just leaving the 'Integrated Windows authentication' checked in the directory security for QvAjAXZfc virtual directory?
1. make sure that in the virtual directories QvAJAXZfc and QvJava, in the tab 'Directory Security', the option 'Enable Anonymous access' is disabled.
2. With acesspoint, are you using Java or AJAX clients? because ajax wont give this error in IE, it doesnt care about your browser, do you have Java virtual machine enabled in IE, should be there in the Internet options.