When you navigate in Local Computer Policy and try to open Account Policies or Local Policies
(Local Computer Policy / Computer Configuration / Windows Settings / Security Settings), you receive
Windows cannot open the local policy database. An unknown error occurred when attempting to open the database..

Your Local Group Policy log files may be corrupt.

To fix the problem, delete or rename the following:

%SystemRoot%\Security\Edb.*
%SystemRoot%\Security\Res*.*