Have you tried another driver? is the problem with one driver?
is your version of windows 32 or 64 bit? did you do the tuning without any load on the motor shaft (Disconnected from the ballscrew?)
What is the motor? do you have the dasheet, and how are you connecting (Series or parallel) and what is the current set to?
These drivers are very good, and i personally use these drivers on my mill, and they are near silent and we only autotuned them.