[Ciaran]

This worked for us!!

We had this problem after migrating to Outlook2003. We eliminated it by deleting the Contacts folder(s) and then adding the Contacts folder that was created during the migration. The words below come from Microsoft :

http://office.microsoft.com/en-gb/assistance/HA011309891033.aspx

To delete the Contacts folder from the Address Book, do the following:

On the Tools menu, click E-mail Accounts.
Click View or change existing directories or address books, and then click Next.
Select Outlook Address Book, and then click Change.
Select the Contacts folder that you want to remove, and then click Remove Address Book.
Exit and restart Outlook.


http://office.microsoft.com/en-gb/assistance/HA011127401033.aspx

To add the correct Contacts folder
In the Navigation Pane click Contacts.
Under My Contacts, right-click the Contacts folder you want to view in the address book, and then click Properties on the shortcut menu.
Click the Outlook Address Book tab, and make sure that the Show this folder as an e-mail address book check box is selected. If the check box is unavailable, you need to add the Outlook Address Book to your profile.


how to add the Outlook Address Book to your profile

On the Tools menu, click Email Accounts.
Click Add a new directory or address book, and then click Next.
Click Add.
Click Additional Address Books, and then click Next.
Click Outlook Address Book, and then click Next.
Click OK.
Restart Outlook.
Click OK.