cd 100/pc freezing up??

[urbanimports02]

so i finally got my new bearings installed in the spindle, and my nm-200 is running better then ever. however, as of lately the screen will go all weird with colorfull lines running up and down and the display is frozen and the machine stops. this has happened several times over the last few days and is getting more frequent. it always does it at the end of a cycle at m09 m05 and before z retracts to tool change position. not sure that has anything to do with it, but kinda weird that it is always at the same line of code, but in different programs, and at different spots in the program. i restart the computer and all comes back on fine, and i retouch off, and all is well for a few more cycles, and it does it again. some of these cycles are long, some short, but thankfully it only does this at coolant/spindle off. any thoughts?

[urbanimports02]

i have narrowed it down to m09 causing the shut down. i just tested it without 220v going to the mill, so no power to spindle or coolant pump, and also isolated the m09 and m05 codes, and it does it now every time at m09. i am thinking it is either mach, or the coolant pump relay. any help as to how to test is appreciated. thanks

[urbanimports02]

also got it to reproduce just by clicking the coolant pump button on mach screen. turn it on then off, does it intermittently when clicking off(same as m09) i took the back cover off the mill and unplugged the coolant pump relay, and then it doesnt do it anymore. i clicked it on and off several times and all is well. plug the relay back in and it does it again. it makes the "bonk" sound that an estop makes as well???? i have disconnected the coolant pump to make sure it is not the pump itself. it is as if the relay is transmitting interference back to the bob which freezes the pc as well? this is really confusing.