Can you open your Device Settings page (press F3) and take a screen shot of the Ports and Laser Settings page and post it here?
One of the settings on that page is a trigger to start marking from an external input pin. If you have it set to something other than ‘None’ then the software will be looking at the state of that input pin and using it to trigger marking. This is normally used with a foot switch, but if you have nothing connected, that would be a problem.
