New Post: Cannot Open CoreConfig in Windows Server 2012 Core and Hyper-V 2012

If you're running from the extracted zip, make sure for each file you follow the following steps:

• Open Windows Explorer
• Browse to extract directory
• Right click a file
• Select Properties
• Click "Unblock"
• Click "Ok"
  

Follow the same procedure for every file and then trying starting up Corefig again. It's annoying, but it fixed this issue for me.