I have the same problem, the e-stop in the middle of the job. Sometimes it will go 2 or 3 minutes, then 15 or 16 minutes, so forth. After checking the history,below the Reset button, it would always stop after the comment "Too Fast For Pulley..using Max. The problem is, I have a CNC Router with direct drive, no pulleys. In the spindle pulley setup under the config tab, I tried various settings on the max speed, setting it very high (30,000 rpm) to Zero. Increasing it to the higher number increased the time before shutdown to about 25 to 30 minutes. I'm still working on the problem. I hope I can figure it out before I pull all my hair out. If anybody has any other suggestions, I would appreciate it.