Since Microsoft has introduced the new UI (previously called Metro) with Windows 8 and Windows Server 2012, you can not start multiple instance of a same program if you launch it using Metro.

Try this:

  • From session opened on Windows 8 (or Windows Server 2012), hit the Windows key to make Metro appears
  • Type notepad
  • Windows finds Notepad and you can launch it by hitting Enter key or click on the result
  • Notepad is launched >> Ok, fine
  • Now, repeat the previous operation
  • Windows returns to the previous instance
  • Now, try using the Run command (Windows+R), you can start as many instance as you want using the Run command

What a mess !!!!!