Stepping motor skipping

I have just completed putting together a system for my 5400 Sherline
mill using the Camtronics 2A 3 axis board. I am trying out the
TurboCNC program but the steppers keep skipping steps (during manual
jogging the system, no load). It seems to skip primarily during
accelleration and decelleration portions of a move, although it also
skips some once it is up to max speed (just not as frequently).

I have searched the archives and tried many of the initial settings
suggested and have tried varying the parameters one at a time but I
haven't seen any improvement. My setup is currently (as of last
night) as follows:

Power - 18VDC
160 oz-in steppers - the step is set to 0.000125
pulse width - 50
min speed - 100
Max speed - 1000
Running TurboCNC in DOS mode on a P90.

Any additional advice is very welcome!

Bob Sweeney