Changing Windows Firewall Settings with Advanced Security Properties
Make any changes desired and click OK two times to close both dialog boxes.
Windows 7 saves your changes to the Windows Firewall advanced security properties.
The default behavior for Windows Firewall is to track outbound connections and allow inbound responses to any established connections. However, this behavior assumes a one-to-one connection (one source going to one destination, or unicast). When a computer sends out a multicast (one source going to many destinations) or broadcast (one source going to every destination on a network) message, the unicast response from the various destination computers won’t be allowed back to the source computer.
Allowing unicast responses under Windows Firewall with Advanced Security temporarily permits unicast responses from any destination responding to a multicast or broadcast message, for up to four seconds.