Allowing unsecured communication may expose your network to security risks by allowing IP traffic to be sent with no authentication ...

Allowing unsecured communication may expose your network to security risks by allowing IP traffic to be sent with no authentication or encryption.  On a computer with Windows Vista or a later version of Windows, this option allows unsecured communication to be sent anytime a secure connection cannot be established. On a Windows 2000, Windows XP, or Windows 2003 computer, this option allows unsecured communications to be sent only when the remote computer does not support IPsec.  Are you sure you want to allow unsecured communication when secure communication cannot be established?