Hello,
I just bought a plugable UD-3900. However, I have barely plugged it in, before it starts complaining about “USB Device not Recognized”.
I have tried to plug and unplug the device, restart and reset (took out the power and USB cable, waited for a while, replugged). I have also tried to connect without any other devices connected to the dock. Nothing works, but it will sometimes cause the USB ports to work, however the stability of them seems to be varying. I have once gotten a monitor to work with the DVI connection, but after unplugging that is now a thing entirely reserved for the past 
I hope you will be able to help me.
I am looking forward to start using my dock!