I really need help on this, I've been trying to fix this for 3 days and I'm not getting anywhere, I can't find anything wrong, and I can't find anything through google. This is a production server, it's been working fine for almost a year. This is a windows 2003 x64 R2 primary domain controller Saturday, I applied some critical updates and rebooted it, and now (for file sharing) it won't authenticate me from any machine that is NOT a member of the domain. Example: I log in from a computer on the domain and open \\server\share\ and it works fine. I try to log in from a laptop or home computer that is not a member of the domain, and it won't accept the username \ password. However, I know the password is good and there is IP connectivity because from the laptop I can ping the server, RDP into it, and access exchange server. It just rejects the username / password without any explanation or error if I try to access a share. This problem affects multiple accounts. I already know what some of the responses are going to be, so I'll go ahead and clear these up: 1. Firewalls are not an issue, I've tried disabling them. 2. I have all the syntax right, I've tried username username@domain and domain\username, nothing works. 3. I am definitely 100% using the right password. 4. IP connectivity to the server is fine. 5. This was working fine, it quit working Saturday, apparently. I'm afraid one of the updates changed some security setting but I have no idea which one.