The thing with NT Services is they can run as soon as the pc is started before anyone logs in - they basically run independantly of any logon.

When dealing with office application & Outlook especially, many of the functions & routines require a logon - i.e. starting Excel, office may look for the current user's name, then check for the default template for this user before opening up a new workbook, okay so not the greatest example in the world as this doesn't really take effect in service code, but it gives you the idea - office apps re always looking at the current user & checking settings.

To get around this, you can force the service to logon with a network account & office will pick up all of this accounts settings. To do this one, go into to the service manager (control panel > services), and set the account information here. In windows 2000, you right click the service, choose properties & the logon tab before specifying an account to log on as...