Outlook 2000 Adress book issues

My company President has been having reoccuring issues with his Outlook 2000 address book. When he attempts to add a new contact, the process appears to work, but then when you go to look for the new contact in the list, its not visible. If you then try to add the contact again, it pops up a window saying “Contact exists, would you like to update one of the following” and lists the desired contact 2 times. Is there anyway to troubleshoot and fix this? Also, he seems to have 2 “Contacts” lists in Outlook (which I am sure is part of the problem). How do I remove the second (blank) contacts list?