From what I have read on this thread I would suggest you, download the manual, uninstall all Focusrite software, run a registry cleaner and then follow the manual for installation.
As I am still a XP 32bit peep I cannot tell you how to check your USB states I sus-p-e-c-t it is much the the same i.e. Control Panel, System, Hardware Tab, Device manager, Check properties of USB devices, power management unchecked allow system to turn off tick box.