sunrise:

  1. Have your Macbook open and running without any peripherals plugged in.
  2. Plug in your keyboard and mouse (or usb hub with mouse and keyboard attached to the hub).
  3. Plug in your external monitor.
  4. Close the Macbook so that it goes to sleep.
  5. Use the keyboard to awaken the Macbook.
Both external keyboard and mouse should work now!

This is pretty basic, but it’s something people should know about. If you have a MacBook it’s like having a laptop and desktop all in one