This problem may occur on a fresh installation of Window Server 2008.
- Click Start, type
in the Start Search box, right-click cmd in the Programs list, and then click Run as administrator.
If you are prompted for an administrator password or for confirmation, type the password, or click Continue.
- At the command prompt, type the following command, and then press ENTER:auditpol /set /subcategory:"Network Policy Server" /success:enable /failure:enable