I can see how someone could forget to add users or that the password matters.
I have an old linksys 20GB Network Attached Storage unit. This unit works great with all my windows 2000 computers, But it does not work with any of my Win XP computers.
I can see it from Explorer, but when I click on it, I get an error "\\Netdrive is not accessible. You might not have permission....Contact the administrator..."