BTW my fridge and the small magnifier ring light both cause enough EMI on the power line here to cause a USB disconnect. Probably the source of much random noise. Half the time when the fridge turns on, cgminer re-inits the KLn device. They're on the same outlet circuit.
How have you connected the outer shield of the usb plug to gnd?
I have often seen at various hubs - that the other shield is also connected via some ferrite beads to gnd.