W2K application permissions on NTFS

Windows 2000 professional with an NTFS partition. Administrator of Domain can access any application, local Admin, Power Users, Users, cannot. The applications have been shared and each user has permissions to the files. The application is Client Access for AS400 connection. The Event log ” Windows cannot unload registry file” Does anyone know what the problem is? Or, can someone tell me how to share applications for all users. Thanks,