I recently "upgraded" to an IBM ThinkCenter PC (1.5gig Pentium, 1g RAM, G-force video card, Windows XP) on my milling machine, and it has been missing occasional steps ever since. I've run through everything I could find on the forum (checking video settings in bios, optimizing services, motor tuning, pulse settings/speed, etc.) and it still misses a few steps every 30-45 seconds. (My ear has been well enough practiced that I can hear the faint "chirp" when it happens). When I recheck the position at the home switches after hearing the chirping, it seems to move a couple of thousandths of an inch each time. Swapping video cards/drivers had no effect.
After messing with it for a week or so, I took the PC from my old Mach controlled router (667MHz Pentium, 256 meg RAM, Windows 2000) that has run reliably for about 5 years. After transplanting the correct .xml file, it runs the milling machine perfectly...
Obviously, the solution is to replace the computer, which I plan to do. I'm really just curious if anyone has any thoughts on what in the world would cause a much "better" computer to not be able to run Mach?