Issue: USB device sometimes fails or doesn’t work all the time.
Resolution: Turn off the Windows power management setting on ALL the USB ports.
Windows XP: Click Start>Control Panel>System> Hardware >Device Manager.
Windows 7: Click Start>Control Panel >Device Manager.
1. Double click Universal Serial Bus controllers.
2. Right click USB Root Hub (and USB Generic Hub, if present).
3. Click Properties.
4. Select Power Management tab. Uncheck “Allow the computer to turn off this device to save power”. Click OK.
5. Make this change for each USB Root Hub.