super-tech

well, I fired up my 4-year-old super-tech stepper-drive mill again last
week. After a controller box exchange, 4 or 5 software3 upgrades, and
a lot of aggravation, it still randomly drops steps and ruins
workpieces, and occasionally doing a manual move from the keyboard
causes a reboot of any of the several computers I've used to run it,
each with it's own keyboard. There's no rhyme, reason or pattern to
it...just every so often it's like it just fails to output to one of
the stepper motors. I've about given up on it, and I'm looking for any
input anyone can give as far as how to keep production running...which
of the available CNC conversions has anyone used and seen fit to
comment on, positive or negative? I'm not looking for another hobby
debugging CNC stuff, I have parts to make and people lined up to buy
them...and I'm severely undercapitalized currently.

Thanks.
Lurch