Group Policy settings do not apply.

I am running a Windows 2000 server with 46 workstation. I have install server Pack2. When I first set up the Group Policy settings, each workstation had the setting applied. But I install Norton Ghost in three of the workstation and those workstation have not taken the Group Policy settings any more. I deleted the Organizational Unit and created it again. Now none of the workstation have the Group Policy settings applied. What should I do?