POP3, Windows Client

This is a help request for the complimentary Comodo email cert.

Two users on a POP3 server.

USER-A is running MS Outlook 2010
USER-B is running Windows Live (Win 7 mail client)

Both users requested a unique Comodo email cert from their local computers. Both users can send digitally signed messages.

Users cannot save signed addresses to the address book. Users cannot send encrypted messages.

From USER-B’s computer I tried to save the signed addresses to the Windows Live address book; the contact already existed, no warnings were displayed. The existing email contact was corrupted; no messages addressed to this contact would send with or without encryption.

From USER-A’s computer, I think I saved the signed email address to Contacts, but I couldn’t send encrypted messages.

Please advise.