I don't have Mach3 installed anywhere, but downloaded it into an XML editor and can immediately see why the pulse width setting would be an issue. This is a classic case of bad design in XML. An XML document should be absolute and the units defined...

If I wrote a document that contained this snippet:

Code:
<price>100</price>
and another that said

Code:
<price>145</price>
what would you surmise?

But if i wrote

Code:
<priceGBP>100</priceGBP>
and

Code:
<priceUSD>145</priceUSD>
you'd get it and it would work anywhere...

Even better would be...
Code:
 
<price>
  <amount>100</amount>
  <currency>GBP</currency>
</price>
In the file you sent the 'pulsewidth' is 19551... but 19551 of what??? and thats the issue... probably relates to machine clock speed or something... which would explain the issue Steve saw...

Incidentally there is no node whose name suggests anything meaningful as regards incremental or absolute arcs, which makes me wonder if its in the file as a default at all until someone changes it, then gets saved as a preference. Maybe the default setting is whatever happens to be in memory at the time the program is first loaded?