Turn off Test Build Windows for valid Win OS user

1. Click Start, and then type cmd in the Search box.
2. Under Programs, right-click cmd.exe, and then click Run as administrator.
3. At the command prompt, type the following text, and then press Enter: bcdedit /set TESTSIGNING OFF.
4. Close the Command Prompt window, and then restart your computer.

https://support.microsoft.com/en-us/kb/2509241