We have an older (@1990) Mazak 655/80N mill with a M-Plus control that has had two very odd crashes in the last 4 months on two different part programs. The mill runs 8 dedicated ISO programs and the operators only load parts, select the desired program and cycle start.
1: 9-15-2021 The first crash happened when the drill missed the target position and drilled into the workholding clamp. Operator hit Reset before I got there so I could not see the program status.
We G10 the work coordinates and they were correct and there was no corruption of the program (o4551) file.
Investigation revealed that the control had changed the sign of the X coordinates from positive to negative causing the the tools to attempt to engage the part in the wrong location. Programmed position X2.375 Y22.627 Actual Position X-2.3749 Y 22.627
The damaged components and tools were replaced, the mill power cycled and re-homed and it ran with no issues until 1-05-2022.

2: 1-05-2022 The program (o110488) was started and it appears the tool went to the first target X-Y position and the correct Z rapid plane then moved minus-X until it over-traveled. Operator Reset again.
Work coordinates were correct and the program was not corrupted.
Programmed position X4.391 Y-21.500 Actual Position X-25.006 Y-23.6875 X at over-travel Y unknown coordinate that is not in current program.
The damaged tool was replaced and the mill was homed then shut down for tooling repair.
The mill was powered up and homed this morning then the same (o110488) program was run with no issues and it has continued to run trouble free so far.

This appears to be some type of control processor or memory failure and I have a call in to our service provider and hope they will be able to identify the problem and get it repaired. Has anyone had this same type of failure and if so what was the cause and solution?
Thanks,
Steve