I am running a simple Mach3 program on a capable PC, but after 1 or 2 hours into the program the computer turns itself off. Its not a power issue or a power settings issue, and it shuts down at different points of the program every time. The program is a 10000 cycles of back and forth between the same sets of co-ordinates. Can anyone help me?

A shot in the dark but it may be an over-temperature issue with your PC. Perhaps blow it all out with an air-line - paying particular attention to the PSU and the processor heat-sink cooling fins etc.

Tweakie.

Are you doing anything else on the PC when it turns off?
What are the PC specs?

My PC will sometimes reboot if I copy files when Mach3 is running. But if I don't copy files, it's rock solid.

Sounds like a PC power supply problem. I had a Dell desktop running XP that started doing the same thing. Cooling fan was running and cpu heat sink nice and clean. Power supplies are fairly cheap on Ebay. Replaced it and no issues.

I cleaned out the CPU fan and it works fine, thanks for your help. I should have thought about the hardware in the first place