Why can't I change a Windows Defender setting?

If your computer is part of a network at an organization such as a school, government agency, or a business, your organization's system administrator might have disabled Windows Defender settings by using Group Policy. Group Policy is a feature of Windows that lets system administrators manage users' access to Windows features or to settings that can affect all users on the computer. If you can't change a setting that you need to access, contact your system administrator.

If your computer is not part of a network, a user with administrator privileges might have modified Group Policy on your computer to remove access to the settings. In this case, contact the users who are administrators on your computer to modify the settings you'd like to change. If Group Policy has not been applied to Windows Defender, you might need to log on as administrator, or ask an administrator to log on and change the setting.

For more in-depth technical information about Group Policy, go to the Microsoft website for IT professionals Go to http://www.microsoft.com and search 'Vista resources for IT professionals'.