JSI Tip 6443. Your USB device does NOT work when you plug / unplug it while the computer is hibernating?

In addition to NOT working, your USB device has a yellow exclamation point (!) next to it in the Unplug or Eject Hardware dialog.

You must NOT insert or eject hardware when your computer is hibernating.

To eject the device, your computer should be running and you should use the Unplug or Eject Hardware Wizard.