Hi,
after the installation of Airfoil 3.5.2 i got an error message on Windows 7:
Could not load type 'System.Windows.Input.ICommand' from assembly 'System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.

I installed .NET Framework 4.5 afterwards and now it is working like a charm.

Bye,
Scotty