USB - Unknown Device

[JimmyinSG]

I had a program that must be run on Win 7 and the licence is contained in a USB. The USB is protected. Win 7 stated as Unknown Device.

So, I tried to mount a USB flash drive onto the Win 7 Guest as a test but the Win 7 is unable to recognize it. It just stated as Unknown Device. The device has stopped working. The flash drive is SanDisk.

I tried to find posts that help to solve this issue but it seems there are only posts on how to mount the USB on Win 7 guests and there are rarely issues on "unknown device".

I use Virtual Box 4.1.8. Mac OS X 10.7.3 as Host. Win 7 Professional SP 1 as Guest.

Thank you very much for your help.