Our intranet site uses NT Authentication. We have recently moved our
intranet to a brand new Windows 2003 server. Whenever a domain user
goes to a certain page, they are prompted to log in again. Adding to
the strangeness, the user can cancel the logon dialog and everything
works, they do not actually need to logon, they just get an
unneccessary prompt. If they are an administrator, they are not
prompted at all on any of the pages.

The only connection we have been able to find throughout all the
problem pages are that they all contain an Excentrics World Calendar
control (v1.9). We had no problem with this control in Windows 2000.
We thought this control was the sole cause of the problem, but we took
it completely off the page, and it still had problems. We also created
a test page which only included the control and a domain user could
view this page with no problems.

We also have an identical (as far as we know) VM set up with the
intranet and it does not duplicate the issue.

On all pages except those with the calendar control NT Authentication
works correctly. On pages with the Calendar control the users are
presented with an NT login prompt, as if the user doesn't have rights
to some resource on the server.

We have checked the permissions and everything seems ok. I have
verified through performance monitor that no anonymous requests are
sneaking through, thus the user is authenticated.
Any ideas?

Thanks,
Amy