SymptomsQuite often, the Windows 7 virtual machine fails to join Home Group if it is started in Bridged:Airport networking mode.
Instead, Windows machine will continue to be a member of 'Unidentified network'.
Usually switching back to Shared Network, for some time, then switching back to Bridged:Airport helps Windows to recognize the Home Group successfully.
Resolution1. Open the virtual machine configuration;
2. Go to Hardware tab and click on Network 1;
3. Uncheck the "Send the host's MAC address to DHCP server" check-box.
4. Switch to Windows and assign a static IP address in the Local Area Connection properties.
Note: If the above does not help, the only solution is to use Shared Networking mode for your virtual machine.