How to disable power management on USB Root Hub
Some USB devices do not work well with power management enabled on the USB hubs in a Windows computer. Disabling the power management can help with this problem.
To turn off the power management for USB hub devices in Windows, open up the Control Panel from the Start menu.
In the Control Panel, select System (in Vista and Windows 7 you need to select the classic view of the control panel for this).
Next, select the Hardware tab in the System Properties dialog box (in Vista and Windows 7, first click the Advanced System settings link).
Now click the Device Manager button to open up the Windows Device Manager.
Open up the Universal Serial Bus controllers, and then right-click each USB Root Hub.
In the popup menu, select Properties and then click the Power Management tab.
Now clear the checkbox called Allow the computer to turn off this device to save power.
Click OK and close the Device Manager.
If you know to which USB Root Hub the USB device is connected to, you only need to do this for that USB Root Hub. If not, just disable the power management for all the USB Root Hub devices in the Device Manager.