Migrating Netware 4.11 to Windows Server 2003

We are planning on migrating our netware 4.11 server to Windows Server 2003 and at present are carrying out some test runs. We are using MSDSS with Novell Client32. The problem we are experiencing is that the migrated user groups are missing some users. It seems that users who have been more recently added to a group are still there in the Active Directory but earlier additions to that group have not been brought across. I can’t work out a “cut-off” date for the addition of users but it may coincide with an upgrade from Netware 3 to 4 with users defined in 3 not migrating. Has anyone seen this problem?

Thanks
Dave