Can’t find the network adapters in MacOS X (10.6+)?
Try unchecking / checking back the option under Parallels Desktop 5 Preferences …

If network connectivity from Windows XP/Vista gone, try this:

Open Command Prompt in Windows (Start > Run.. > type ‘cmd’ > OK)

And enter following command:

netsh winsock reset

Restart Windows and use next command:

netsh int ip reset reset.log

Restart Windows once again.