Q: usb device using too much power message

I get this message when I turn on the computer. Nothing in any of the USB ports except the wire (in good condition) to the keyboard. The message box keeps reappearing even though I click "ok." But after several repeats over a few minutes the box disappears and I can get on with whatever I'm doing on the computer or the Internet.

What is causing this false alarm and how do I stop it?