Checking Email Addresses Against Contacts

I have 2 seperate but related issues. I am using Exchange 2003 with Outlook
2003/2007 clients.

1. I have one Outlook client that, when pressing the Alt-K key for example,
will not validate against the Users Contacts in their personal mailbox. As
a matter of fact there is not even a dropdown to see that list from the
Address book. I know I just missed something.

2. Is there a way to have an Outlook client validate email addresses
against a contact list in the Public folders? How?

Thanks!

-Richard K