*For Microsoft Windows Vista (and windows 7)
Click Start, and type device manager in the Start Search box.
Click Device Manager in the Programs list.
If you are prompted for an administrator password or confirmation, type your password or click Continue.
In the Device Manager dialog box, expand Universal Serial Bus controllers.
Right-click USB Root Hub and then click Properties.
In the USB Root Hub Properties dialog box, click the Power Management tab.
Remove the check from the Allow the computer to turn off this device to save power check box. Repeat steps 1 through 4 for each USB Root Hub listed in the Device Manager.