The setup: Two Windows 8.1 pro boxes. Each one has a different MS account associated with it. Box A has a shared folder. Premissions set with "everyone" rw. Box B is trying to access the share. When Box B opens Box A in the network it prompts for credentials. (box that pops up is shown below) Box A will accept any username entered, but it will always pop up the box asking for credentials. Why is this happening? I noticed that it is using the computer name for the domain, is that normal? Why would it even need to show the box if the everyone group is added to the share? I've tried everything I could think of, nothing works. It's not just Windows 8.1 that cannot access the share, even a Windows 7 box gets the same popup. My network setting have password protected sharing disabled, and use user account, not homegroup is selected. Network setting are identical on box A and B.
If this is your home system you could go to network and sharing center, then change advanced sharing, then turn of password protection for all networks. this should be done on the system with the shared folder.
Like the original post said, password protected sharing is off for all computers, and to add all networks are set to Private
When you turn Password Protected Sharing to Off, what Windows actually does is to enable the built-in Guest account and give it rights to access the computer over the network, but not to log in locally. If you have made any changes to the Guest account yourself, that may interfere with this, for example if you have given the Guest account a password. If you have not made any changes to the Guest account, then when you are prompted for credentials on any computer, you can gain access with any username, as long as you leave the password empty. What actually happens is that Windows tries to log in with the username given, and when that fails, it automatically falls back to the username "Guest". The computer name showing up as the "domain" is completely normal, don't worry about that. Lastly, the reason why you are prompted for credentials is to give you a chance to log in with a username other than Guest, which may have more permissions than Guest. This is by design.