The xml is a file that stores your config settings and if yours is a standard machine from a manufacturer that is set up to run Mach then they may supply you with an xml so that you dont have to config things yourself.
Your problem however seems to be port related as if Mach is not communicating with the port then you will never get the machine to run. Can you attach your xml for the profile you are using and I will see if I can find an issue.
Hood

Profile says Mach3Mill. I do not know how to pull that file up and send it. Sorry

Ok look in the main Mach3 folder and you will see a file called Mach3Mill.xml copy it to your desktop and rename it to Rideredcr.xml then use the additional options on the reply page to browse to your desktop and choose the renamed xml.
The reason you need to rename is the forum only accepts a file name once and Mach3Mill will definitely have been attached before.
Hood

ok thats what I thought. I didnt see it before but ill look again. give me a sec

ok tell me if you can open it

Ok all looks fine except you have the step pins as 3, 5 and 7  and Dir pins as 2, 4, 6. Measuring voltage at the step pins will likely show a small enough voltage that your meter wont register unless you are on mV range (depends on active state) So recheck on pins 2, 4 and 6 with a Gnd pin.
If that doesnt help then for some reason your port is not being seen by Mach.
Hood

I haven't changed anything, but now I'm getting 104.5mv when I  jog in the + direction. The voltage stays at 104.5 until I jog in the - direction, in which case the voltage goes to 3.5v and holds there until I move in the + direction. Is this normal? By the way thanks for all your help!

Yes if you are looking at a Dir pin then that would seem about right. You may have issues with the port only putting out 3.5V, some breakout boards can handle the modern low 3.3v ports others cant. If yours cant then getting a PCI parallel port that puts out 5v will sort you out.
Hood

Ok Im going to try that........but I just tested it again....... and now I'm getting -99mv in the - direction and -250mv in the + direction..........I hope a new board work. Thanks for the help.

Sorry to keep asking dumb questions but I am trying to establish what you have.

Inside your control box do you have the genuine Microproto controller or is it a Stepmaster board ?

Tweakie.