Hi,
you don't say what motion controller you are using.
I use an ESS and you can if you run other software when Mach is running cause the ESS data buffer to run out. Usually though it posts an error code if that
happens. If memory serves though, there is a setting in the ESS plugin that enables/disables the buffer monitor. It may be your buffer is not being monitored and
could be stopping WITHOUT notification.
I run a dual core Atom based single board PC for my machine controller, a very VERY modest computing platform and worse uses on-chip graphics so falls well
below the NFS recommended minimum specs. I run 32 bit Windows7 so in effect have about 2.5 gig of RAM despite 4 gig being fitted and I run PCB routing
programs of up to 100,000 lines. I doubt therefore that your PC is running out of puff.
I rather suspect that noise is affecting your estop line. It might be difficult to prove given that it happens so infrequently. May I recommend fitting a small capacitor,
maybe 470-1000pF to your Estop input at your controller to earth. Certainly can't hurt.
By the way Fusion 360 is a 64bit only program, so if you are running Fusion on the same PC as your machine then your PC MUST be 64bit.
Craig