has anyone experienced the computer booting and driving the cnc machine z axis 2.5 inches down and on a shutdown the cnc machine z axis clitches about 1/2 inch
Cannot uinderstand ,the printer port is standard and the right address and it is a desktop amd 3500 computer 2 gigs ram xp pro

Usually when booting a computer the operating system interrogates the parallel port, this toggles Inputs and outputs on and off and can cause motor movement. Usually it is just motor twitching but sounds like your is more serious. There are a couple of things you can do, the most obvious is have the drives switched off until the computer has booted or if your breakout board supports a charge pump use that.

Hood

I hear what you're saying ,I used to have just a clunk noise on re-booting but now the z axis drives 2.5 to 3.0 inches down while xp comes up.
The manufacturer recommend leaving the cnc turned off  but my thoughts are  if the project was cutting and the machine got a glitch it would drive itself into damage.
I never had this before this just developed recently.
I also tried all the settings ecp.epp etc but its all the same.
Manufacturer says it s noise interference......hmmmmm