On a computer that is running Windows Vista or Windows Server 2008, you enable the “Run logon scripts synchronously” Group Policy. When you try to log on, the Welcome screen may be displayed for 30 seconds. Then, the logon script interacts with you before the logon script process continues. For example, the script prompts you to confirm a dialog box.

Note: The “Run logon scripts synchronously” Group Policy setting is in the following location in the Group Policy Management Console:
Local Computer Policy\User Configuration\Administrative Templates\System\Logon\Logonff