This is the most common problem that I encounter when we make a home network using Windows Workgroup that Windows starts asking for username and password when we try to access a shared folder across the network. The worst condition comes in when Windows asks for only the password. The user name is defaulted to ComputerName\Guest and the field is disabled. I have never been able to logon using ANY password under this situation.
While there are many other reasons for this password protection, one of the solutions that I have found out is an interesting one .. I’ve observed that if we disable the guest account in Windows, that freaky guest login also disappears. To disable the guest account, do the following:
Go to Start –> Run –> compmgmt.msc
From the left hand pane, select Local Users And Groups –> Users
In the right hand pane, right click Guest and go to properties.
Check “Account is disabled" option.