I am having the same problem, only I get error 6762 or 8877when I run the spindle after just a few seconds. If I hit yes to recover the then I get error 9991. Either way Mach3 crashes. Also I have to toggle the spindle relay from the DSPMC to make the spindle go. Even though I have Mach3 set to use the relays.
Things worked fine on an XP system. Am I doing something wrong, or do I have to go back to Win XP?
I haven't even set up the servo axis yet because I'm not sure any of this will work at all now.
My setup:
Win7x64
DSPMC controller with current firmware.
Teco VFD with 0-10V input, output1=forward, output2=reverse
iMach P3 pendant.