Sometimes when you reboot, the USB circuits (if you will) still remain energized. Ensure all USB devices are off. The things I do are... Reboot w/ USB, make sure you have the latest drivers, on everything, unless you have a controlled operating configuration. Also with KORG their may be two drivers...1)Configure KORG USB-MIDI Driver app and 2) Configure KORG driver setup utility. You have to play with both sometines. bRAD