XP Address Book totally deleted, WHY??

[XP-Home,+ NAV,Anti-Spam, Firewall,SystemWorks 2004,Ghost,DSL connection].Two users on computer, user1’s address book deleted,user2’s not.What caused deletion of Address Book #1? Have tried a “Find”. Ghost backup did not work for lost info.(NAV virus option in both set to delete not -repair/quarantine). Keep all virus definitions updated daily. Virus scan computer regularily. Does anyone have an idea about this problem? Regards, eroberta