"usb device was drawing too much power" error message

Ever since I upgraded to Lion, I've been getting this error message a lot. It seems to trigger(not every time though) when I plug in my iPhone to the usb port on my keyboard.

The only other USB device that's connected to my brand new 27" iMac is my printer. I'm using a Magic Mouse. I've never had this problem before prior to upgrading to Lion. What's causing it how do I make it go away?

Solution 1:

If you plug your iPhone with your keyboard the total power requested by you keyboard (i.e. iphone + keyboard) is too high for the usb to handle. I suggest you plug your iphone directly to your iMac.

Solution 2:

Check that the USB port is still functional. I've had the same issue, but have now found that the USB port isn't working irrespective of the device that is connected to it. Discussion over at Apple here (but no replies yet):

https://discussions.apple.com/message/17202737#17202737