A couple questions here...... Helping a friend, my mach 3 install (With custom screens) works fine.  No problems what so ever.
Exact same install on another pc/same controller.  He is getting random script errors when trying to home.

I have compared his XML to mine.  The only difference I can see is that in his motor outputs his DIR low active is checked and mine are not.  To my knowledge all this field does is reverse the motor direction.  So, first question, is that all this field does?  It seems a little redundant to me to have the DIR low active and the reverse field in homing/limits.

What would cause random script errors on an install that is widely used and no other issues reported with the customer base that is running this version of install?  My best guess is computer environment.  To the best of my knowledge, the computer is clean with no A/V no QTime.  Win XP

The active state is not redundant as some drives are very fussy about it, some will not care but best to look at your drives literature to see whether the are active High or Low for Step and Dir signals.
 Try copying the macro folder from the good computer to the bad one, could be a screwed up macro.
Hood

Here is the documentation I was able to find on the drive in question.  Im not going to pretend to understand exactly what it means.  If someone can understand the technical side and give me a direction that would be wonderful!
Connector P1 Configurations
Pin Function Details
PUL﹢(+5V)
PUL- (PUL)
Pulse signal: This input represents pulse signal, effective for each rising edge;
4-5V when PUL-HIGH, 0-0.5V when PUL-LOW. For reliable response, pulse
width should be longer than 1.2ms. Series connect resistors for current-limiting
when +12V or +24V used.
DIR+ (+5V)
DIR- (DIR)
Direction signal: HIGH/LOW level signal, correlative to motor rotation
direction. For reliable response, DIR must be ahead of PUL by 5ms at least.
4-5V when DIR- HIGH, 0-0.5V when DIR-LOW. Please note that motor
rotation direction also depends upon the connection of the motor windings,
exchange any motor phase can reverse motor rotation direction.
ENA+ (+5V)
ENA- (ENA)
Enable signal: This signal is used for enabling/disabling the driver. High level
(NPN control signal, PNP and Differential control signals are on the contrary,
namely Low level for enabling.) for enabling the driver and low level for
disabling the driver. Usually left UNCONNECTED (ENABLED).