Hyper-V won't install on x64 Windows 8.1 Pro

I can't seem to get Hyper-V installed.

I am running Windows 8.1 Pro 64

Steps to reproduce:

1. Add/Remove Features

2. Add Hyper-V, and all subsets

3. Click OK.

4. Click Restart when prompted.

5. Computer will reboot and then work on configuring features.  At 91% the computer will stop and display the error message "Unable to add feature..." and then roll back entirely.

Does anyone have any ideas as to the cause and fix?

Thanks,

Daniel