Could you try pushing and holding the scanner key and the side key, this should reboot the unit.
One of the best and the fast response which i got from this group.
Thank you very much. It works.
having the same or similar issue. Windows 7 Pro no longer recognize the USB device and lists it as Unknown Device. When I connect it to my Mac book and try to remove or update files, it completely freeze Finder and the keyboard doesn't respond. Only the mouse responds and the Mac won't even do a shutdown unless I hold the on/off button