I experienced the same problem. The solution as I remember it:
Tools | Account Settings ... | Published Calendars | Change Account ...
Selected "Next" on all questions.
(Got a warning that i would have to need to republish my calendars.)
Did NOT sign out of my Live ID account.

John


"Walter Weiss" wrote:

I am using Outlook 2007 connected to an exchange server.

Whenever I try to publish a calendar or a new calendar that I create to
Office Online or my own custom WebDav Server, I get the message

Failed to publish the calendar "Calendar". There was a problem uploading the
file to the server.

There are no other error messages.