How to fix .NET framework 4 installation error

I got this error when trying to install .NET Framwork 4. If you encounter this window, this may be a solution

1. Go to regedit and look for:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4
2. Change the permission of this v4 key by adding two more accounts named Administrators & SYSTEM with Full Control
3. Reinstall