Can't get out of ESTOP - Gecko G540

My Linuxcnc setup has been working fine, up until today.
After making some adjustments/upgrades to my X-Carve hardware, I did a few tests of the machine to make sure I hadn't broken anything and was able to jog around OK.
A little while later, I went to run a real job, and I can't get it to come out of ESTOP mode.

The FAULT LED on the G540 is not on, the POWER LED is lit. Checking status with the ptest script shows that DB25 pin 15 is LOW as it should be. Using hal-meter under Linuxcnc shows E-STOP as FALSE. A check of the voltage on pin 15 show it to be 0 volts with no FAULT and a positive voltage (can't remember value exactly) when in fault mode. Fault mode was forced by disconnecting ENABLE (pin 10) on the internal G540 connector.

I haven't made any changes to the Linuxcnc configuration. The only computer change was a reboot to get networking connected again.

Any ideas as to where to look next?

Well I've managed to get it going by changing the .hal file to set parport.0.pin-15-in to parport.0.pin-15-in-not.

As I said, I've not made any config changes to the hal file. The only change I made was to the ini file to adjust the X-AXIS MAX_LIMIT from 790 to 760. No software updates have occurred as the computer is not network connected.

I've attached the original configuration in case there's something in there I've missed.

If it would have been Mach3 I could have tried helping. Still trying to understand this stuff.
It is interesting to note that LCNC could also do random unexplained things too. It could be operator error of course, but I have seen many unexplained things on the "other' side.