Our Imacs (white and silver) have Leopard OS and have been updated recently to 10.5.6v. After the updates, user were getting an authentication error connecting to our server which is running Tiger. We tried loading to the original OS version 10.5.1 and still had the same problem. Logging as Admin account doesn't have any issues at all. We are unsure whether the updates corrupt some permission issues at the server. Thanks.