Group policies

There are 15 users/computers in our accounting department. We have created a group policy for their department. The policy changes the background to a company logo background, and takes away their ability to change it. There are 3 computers that havent applied the policy. All computers in the department are Win2000. The policy was created and applied 1 week ago. I have checked to make sure that the 3 pc’s are logging into the correct domain… Anyone have any ideas on what I should checknext? Any suggestions would be appreciated.