Why is my domain-joined computer automatically managing my HomeGroup connection?
When a user logs on to a domain-joined computer that is also a member of a HomeGroup, Windows 7 always connects to other computers in the HomeGroup. This happens even if the Use user accounts and passwords to other computers under HomeGroup connections in Advanced sharing settings is enabled. Windows 7 always overrides Advanced sharing settings, and it manages HomeGroup connections on behalf of the user. The domain-joined computer overrides these settings when the user logs on. When a computer is not joined to a domain, the setting is honored properly by HomeGroup.