If Outlook hasn't been started yet, you can use the Namespace.Logon method to start it with a particular mail profile.

FYI, there is a newsgroup specifically for general Outlook programming issues "down the hall" at microsoft.public.outlook.program_vba or, via web interface, at http://www.microsoft.com/office/comm....program_v ba

--
Sue Mosher, Outlook MVP
Author of Configuring Microsoft Outlook 2003
http://www.turtleflock.com/olconfig/index.htm
and Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx

"DeborahK" wrote in message ...
I am trying to programmatically access Exchange shared and public folders via
Outlook from a .NET application.

Here is the line of code that is generating an error:

Dim olns As Outlook.NameSpace = OutlookInstance.GetNamespace("MAPI")
mapiFolder = olns.GetFolderFromID(folderID, storeID)

The error is:
"The messaging interface has returned an unknown error. If the problem
persists, restart Outlook".

I don't get the error message when accessing the user's default mailbox. I
also don't get the error message if the user manually opens Outlook before
using my application.

The application is correctly loading Outlook using:
' Create the instance of outlook
_OL = New Outlook.Application
I know this because I can see Outlook being added to the Task Manager.

I have been struggling with this for days so if anyone has ideas I would
appreciate them.

THANKS!