Oh, probably you can avoid the reboot by changing the access level to "Service" (username: service, password: service123), choose "Disable all Safety Systems", click "OK" on the dialog popping up telling you that this is forbidden when operating on public rails and having passengers, and just continue driving.
[yes, completely made up, but corresponds to what's happening daily in other, probably slightly less safety critical, industrial automation systems]
Lots of embedded systems reboot themselves when they get into some unknown state. It's the safest thing to do. Microcontrollers are designed to do it automatically in some cases.
People generally don't notice because the system doesn't beep or display a boot message (if it even has a display).
[yes, completely made up, but corresponds to what's happening daily in other, probably slightly less safety critical, industrial automation systems]