When I was having problems with my UC100, I tried many things being described; power saving modes, new cable, re-routing usb cable, etc.
The last thing I did was add a powered USB hub between the computer and the UC100. Since then, I have much better success. I will say, if I had to do it all over again, I would go the ethernet way and avoid USB - seems like a lot of people have trouble with it.
Chris D