1st question is ‘what are the clients?’
Group Policy has grown every generation , more capabilities in 2k3 than 2000 , more in 2000 than NT. The clients can only recognize policies when the appropriate registry entry is available to be changed. Thusly a ‘Groupo Policy Object’ (rule) and only apply to the client if that object is present.
95/98/ME clients are very limited when it comes to ‘Group Policy’.
The 2nd question has to do with local and domain settings. Sometimes the ‘Domain Group Policy’ is trumped by the local policy settings. You need to chack that the client not only hears the policy and can understand it, but isn’t setting back to default locaally.