Another BAND-AID for people using USB motion controllers.
A better quality USB cable MAY help.

 I'm running window 7 64bit I5 CPU and 8gig ram  and i have over 3/4 disk space . i am using a 6" usb cable that came with the uc-100 controller

6" (6 inch) usb cables are included with most (made in China) knock-offs of UC-100.
I think the genuine UC100 came with a 6' (6 foot) USB cable.
Watch
https://www.youtube.com/watch?v=oKU9xN6D06g
He uses a better 15' (15 feet) USB cable for his genuine UC100.

HOPE THIS IS WHAT YOUR LOOKING FOR, IF NOT LET ME KNOW

WINDOWS 7 HOME PREMIUM
SERVICE PACK 1
SYSTEM
DK SYSTEMS
MODEL DK  112134     4/23/12
RAM 4.00GB 3.71 USABLE
64 BIT OPERATING SYSTEM

LUMBER60

HOPE THIS IS WHAT YOUR LOOKING FOR, IF NOT LET ME KNOW

WINDOWS 7 HOME PREMIUM
SERVICE PACK 1
SYSTEM
DK SYSTEMS
MODEL DK  112134     4/23/12
RAM 4.00GB 3.71 USABLE
64 BIT OPERATING SYSTEM

LUMBER60
Modify message

waking up an old thread that is still relevant!

I had intermittent hiccups despite trying buying shielded USB, extra ferrites, and rearranging the power plugs to my equipment to change ground paths. So I starting trying to setup a parallel port.  Bought the cable, found a really old laptop with a parallel port, found out Mach doesn't like those, so setup a desktop pc with a parallel port card I bought, STILL didn't work, then ultimately learned that some parallel ports use 3.3V digital signals instead of 5 and how to identify whether your parallel port card does 5 or 3.3.
In the meantime I had the idea of running the long parallel cable from the motor drivers (Microproto from Taig) to the UC100, then only a foot of USB to the laptop. 
Whammo, not one fault since. I originally had the UC100 screwed to the driver box then USB all the way.
I thought this was worth sharing and I hope it works miracles for you too!

I used a USB motion controller for a long time and after trying literally everything, from changing cable, moving computer, using shorter cable, RF filters, ferrite... I still had the problem of loosing communication randomly when spindle turned on or when I would switch on the hoover next to the machine. In the end I moved on to an ethernet controller and never had a single problem after that. bite the bullet and spend those £ 150, you will not regret it