When you try to add a new vSwitch that is bound to a physical adapter in Hyper-V, you may receive the following error:
Virtual Switch Manager for SOME-SERVER
Error applying Virtual Switch Properties changes
Failed while adding virtual Ethernet switch connections.
External Ethernet adapter 'Intel(R) 82574L Gigabit Network Connection' is already bound to the Microsoft Virtual Switch protocol.
In this case go to network settings and find the affected adapter. Then in Properties remove the checkbox that binds Microsoft Virtual Switch protocol and press OK.
Try to create the vSwitch again.