Outlook Express Address Book does not display the contact information

I have a problem in viewing and adding the contact information into Outlook Express Address Book.

All of the contacts in the folders (Shared Contacts and Main Identity's Contacts) had suddenly been disappeared, and now only one contact can be seen in the Shared Contacts.

However, Outlook Express still allows me to find the e-mail address by typing in the contact name for search. By being able to get the old contact inforamtion that I had once input into the program, I think Outlook Express has the input address data somewhere but does not display it for me.

One more trouble is that it does not allow me to add new address.

I'll appreciate your advice.

Thank you.