Which key is KEY_LEFT_GUI? This might be a very simple question but I don't know which key represents KEY_LEFT_GUI on my keyboard. I thought it was the windows key but when I program Arduino Micro to execute it. Run does not open and it prints powershell on the "Search Programs and Files" section in Windows7 VM.  

  Keyboard.press(KEY_LEFT_GUI);
  delay(1000);
  Keyboard.press('r');
  delay(1000);
  Keyboard.releaseAll();

  delay(500);

  Keyboard.print("powershell");
  typeKey(KEY_RETURN);
KEY_LEFT_GUI is the left Windows key. I think the problem may be that your code is only holding those keys down for microseconds. You need to give the computer a little bit of time to recognize the keypresses because it's expecting a human using a keyboard, not a microcontroller running at 16MHz. Try adding a delay before Keyboard.releaseAll();.