I've got some users with Outlook 2003 on XP SP2 who typically review
and move messages (drag & drop) from their Inbox to a set of
subfolders created in the Inbox of another user. They normally have
this other user's mailbox visible in their folder list.

Recently, they are getting errors of the type 'Can't move message:
Unknown error' when they try to move the messages.

The only thing I have found is that it can be moved without issue if I
try to duplicate the issue on a system with Outlook 2007
installed....leading me to believe the original email was created and
sent with Outlook 2007 and the user will require Outlook 2007 in order
to do this.

Has anyone run into this?

RobC