If you login in Windows 7 and find that Windows have no network connection with A "Unidentified Network", it is caused by the Bonjour DNS Responder Service.
How to fix the error:
Click the start button --> Type services.msc in the search box and hit press --> in the services list, find out
Right Click it --> Select Properties select Disabled from the startup type --> Click STOP --> Click Apply --> Reboot your computer.
Now your network adapter comes up again.