Address Book is suddenly empty - no contacts displayed

All,

First:

I'm using a late 2008 MacBookPro 17" with 4GB RAM and a 320GB HD.

MacOSX Snow Leopard 10.6.8

Address Book 5.0.3 (883)

Mail Version 4.5 (1084)

Yesterday evening I found that Address Book was empty - no contacts displayed and Mail did not recognize the group name when I entered it in the To field.

Actions I've tried but did not resolve the issue:

• Restoring Address Book from a Time Machine backup that was previous to when the problem occurred.
• Deleting the Address Book app
  ~/Library Address Book Plug-Ins
  ~/Library/Application Support/Addressbook and
  ~/Library/Application Support/Yahoo! Sync

And then restoring these same items from a Time Machine backup that was previous to when the problem occurred.

Deleting the Address Book App and then reinstalling from my Snow Leopard Install DVD.

When I restored AB from Time Machine all my entries showed in Time Machine (even the backups made *after* the problem began) all vCards are there and seemingly are restored. But, when I make any effort to use a card or change to a different card, AB quits and it's back to an apparently empty address book.

I have exhausted my limited experience and am hoping someone here can point me in a new direction.

Thanks,

Bob