High stepper rate troubles

[John Weismiller <johnweis-at-home.com>]

Hello all,

I am a hobbyist with a CNC converted Sherline mill using steppers
driven by Geckodrive G201 stepper drives.  I am running emc-0.9-25 with
steppermod.o.

With my setup, I get a INPUT_SCALE of 40000.  This value is so high that
it crashes the computer after the modules have been loaded.  It looks to
me like there are too many interrupt per second so nothing else gets a
chance to run. 

So my question is this:  How do I fix it?  I tried lowering the
MAX_VELOCITY variable, but that did not help.

Thanks,
John.