Could be a firmware upgrade problem.
Try to update it in the follow way ( http://www.st.com/stonline/products/literature/um/17902.pdf )
1)Plug only the STEVAL-MKI062V2 board
a) Download and install the DFUSe from the support url
b) Run the DFU application
c) Start the device in dfu mode --> Plug the usb cable
pressing the button (SW2)
d) The device is recognized as DFU device, then select the
.dfu file from installation folder of iNEMO application under firmware/DFUimage folder and upgrade
e) Press Leave DFU mode --> the device will ask to install
f) Check the Device Manager now in ports you will find the
STEVAL-MKI062V2 device connected
Retrieving data ...