Offizieller Kommentar
Sorry to hear about that guys. We are aware of these complaints, but unfortunately the primary cause of this issue is the computer itself not providing the device adequate power over USB. You can try using a different USB port or even a different USB cable.
If your computer still doesn't provide adequate power, you can test another computer (or 2) to see if they recognize the device, thus ruling out a bad DDJ.
An alternative is to use a "Y" cable to provide additional power from another source (either an external power block or another port on the computer).