Dear Clive.
There isn.t any new problem other than in this video https://www.youtube.com/watch?v=KWlVfyy1hFU. This is the problem I have for over a month ago. I could not fix this.
I.ve changed the enclosure and rewired everything and in the end I.ve got the same problem. Stalling, jerking, strange noise etc.
I use the power supplies included in the kit, for 1200oz nema 34 steppers, in this case S-350-60, 60V, 5.85A, DC Output.
The driver settings are as stated in the first post, ..Dip switches set as OFF OFF ON ON OFF ON ON OFF , which sets the thing to 4.9A Peak, 3.5A RMS, Full Current from SW4 (i don,t really know how to set this), and 2000 pulse/rev. The next current setting is 5.7A peak... And I changed this to 800 rev/min and 1600 rev/min in order to see how it goes.
Settings in Mach3, there are plenty. Could you please be more specific.

Dear Rob,
The yellow exclamation did not exist with the previous installation of windows7. These are all new things the win xp experience.

I.m quite aware by now that you are qualified and smart guys, and know your craft, and I don.t mean any disrespect, but this ..Pulsing to slow.. does not raise any concern to anyone?