Did you ever faced a problem installing a software and process crashed because of the add/remove database, or you uninstalled an antivirus from add / remove programs and you cannot see it any more but when trying to install a new antivirus it points that the old one still exist and need to be removed.
Also if Windows security database is corrupted or If "Extended Error" occur,
Solution is to run these command on windows XP
esentutl /g c:\windows\security\Database\secedit.sdb
esentutl /r c:\windows\security\Database\secedit.sdb
esentutl /p c:\windows\security\Database\secedit.sdb
esentutl /g c:\windows\security\Database\secedit.sdb
esentutl /r c:\windows\security\Database\secedit.sdb
esentutl /p c:\windows\security\Database\secedit.sdb
esentutl /g c:\windows\security\Database\secedit.sdb
