I've been using a different method - I wonder if they accomplish the same result?
Start>Settings>Control Panel>System>Hardware Tab>Device Manager
Go to the bottom of the list, click the little plus sign next to "Universal Serial Bus Controllers"
Right click on the first "USB Root Hub" you see. Select Properties. Go to the Power Management Tab.
Make sure the "Allow the computer to turn off this device to save power" box is UNCHECKED
Do this for all the USB Root Hubs listed.