Outlook Public Folder hompage security issue

[Nour]

Hi
I've set a public folder homepage to an ASP application that is running on
our local intranet. The problem is: each time I click the folder or the page
gets refreshed, Outlook prompts me to enter my login credentials, although
'Automatic Login in Intranet Zone' is set in Internet Explorer and the site
is added to the Local intranet zone. The virtual directory on IIS is set to
integrated Windows authentication.
I have tried with several versions of Outlook and IIS, on several servers,
all show the same problem.
When the page is accessed in IE, the user is automatically signed in without
prompt.

Strangely, when the public folder homepage is set to the virtual directory
(e.g. http://server/virtualdirectoy), it works without prompting for username
and password, however, when it is set to an ASP file on that virtual
directory(e.g. http://server/virtualdirectory/asp/mypage.asp), it prompts to
log in.
Another strange thing is that you can cancel out of the login prompt and the
application works fine, but when the page refreshes (it has an automatic
refresh) the login prompt shows again.
Everyone has full control on the virtual directory and its subdirectories,
and again, in IE it works fine, just Outlook needs me to sign in for whatever
reason.
What can be done about that???

Thanks for helping me out!