MacIntosh client on Win2000 server

We have a problem with mac clients on a new Win2000 server that has been set up for their use.

Although sharing and inheritance has been set up, when a member of the CREATIVE group creates a subfolder (from a Mac client)the CREATIVE group do not have any permissions on that folder.

All other groups are inherited OK. This setup worked OK on NT4.

Has anyone heard of a similar problem? I just noticed that the CREATIVE group is a global group, although this has not caused problems in the past, nor with other global groups.

Any ideas?