Hi Joe,
You might upgrade to V4,34 as well as use Windows Device Manager to update the Drivers to those in V4.34.
Its hard to say, but I think it is unlikely to be any of those if it runs without errors with Motor and Spindle power off.
Sounds possibly like a noise issue from the Spindle or Motor Drivers. Possibly causing Windows to disconnect the USB communication. Or do you have limit switches configured to disable axes that could be falsely triggered by noise?
You might also try running tests with only Spindle Power or only Motor Drive Power to try to determine the noise source.
Can you describe your system with regard to wiring, supplies, grounding, shielding? Is the USB cable short, with ferrite cores, and away from noise sources? Did you check the shield continuity to be less than 1 ohm? You might see
this.
Please be sure to write down exactly what error messages you receive. Also any other possible clues. Such as what the machine was doing, what was the state afterward, etc...