Usb grayed out...USB3 controller with USB2 device

[Mannaggia]

UP, 1 week without suggestions

[Scar8612]

I had a similar problem with my macbook pro retina (late 2013). When I tried to use a flash memory a Windows 7 64-bits the machine didn't install the usb drives, I made some search and ended installed a program called "Slim drives free 2.22" it search for missing drives, download them and infall them, after that the Windows 7 guess was able to recognize the usb drives I attach to it.
Hope this info can help you.

Regards.