Help! EMC problem when trying to use 4th axis to control laser

I switched from using the Z axis direction bit to turn my laser
on/off to using the A (4th) axis in a similar fashion. I did a quick
test file and was surprised to see that it didn't work as planned.
It seems EMC is not happy driving 4 axis (what is the plural of
axis?) on my PIII 600mhz machine. Here is a sketch of what is
happening to one of the circles in my test file (the other circle
cuts perfectly!?!):

http://www.skyko.com/emc/sketch.JPG

Here is the gcode I used (moving A down 0.0001 to change the
direction bit and turn on the laser, moving A back to 0 changes the
direction bit and turns off the laser):

http://www.skyko.com/emc/axistestusinga.txt

If I change back to using Z, like in this file, things work fine:

http://www.skyko.com/emc/axistestusingz.txt

Both circles cut perfectly.

Here is the ini file. I just copied the first axis to make the 4th
axis:

http://www.skyko.com/emc/emcini.txt


So, any idea why adding G00 A0 commands would make the x axis lose
steps??? I am not sure what in the world EMC is doing!


Thanks for any tips!

Rick