Symptom- A USB device does not work as expected when connected to an Apple Pro Keyboard's USB hub, particularly if it draws more power than the hub provides.
- The computer experiences System or other errors when a USB device is connected to an Apple Pro Keyboard's hub.
Solution
Unplug the USB device from the keyboard's hub, and plug it into one of the USB ports on your computer or display.
Notes:
1. The Apple USB keyboard acts as a bus-powered hub. Under the USB Specification you cannot connect two bus-powered hubs together because there won't be enough power for the second hub. See article 43005: "USB: Hub Description" for further information."
2. Apple USB Speakers must be plugged into one of the USB ports on your computer or display because the Apple Pro Keyboard does not provide enough power to make them work.