"Apparently" I've got interference....

Been lurking a long time (while working on my laser cutter)....

Now for my issue. With most of the support equip. powered up (vacuum, water
pump, cooling fan, stepper controller), things start out good then get worse for
jitters....

It makes little or no difference which software (trialing both Mach/Turbocnc),
OS (win98 or xp), or PC (laptop or desktop)... So that leads me to believe that
some stray interference is hoping on the step/dir lines inside my cabinet.

Before I start chasing gremlins (or poor design issues), which means money, I'd
rather look at some "known" issues.

1) I don't currently run a buffered Break-out board. Straight wire from PC to
terminal block then point to point wiring to the stepper driver/controller.
This is my leading thought since the motors go jumpy w/o a pc attached due to
"floating" inputs. Everything calms down if I Power-off/on the controllers
(soon returns).

2) I could start with just the steppers powered up, then sequentially power-up
the laser components. I'm almost ready to "move" all the motion control/beam
control to a separate cabinet (with separate 5v psu) as there are all kinds of
'nasty' things in the current cabinet including a 15kv/30ma transformer.

3) I don't have any more "good" guesses.

Just looking for other thoughts.

Stan