If you are experiencing LinuxCNC Error Window when you try to open the program like this one
If you are trying to start the program multiple times and you get message box "LinuxCNC is still running do you want to close it" click No and wait for the CNC program to start.
Other common reason for this error are hardware changes or fault, or changes in the ini or hal files, changes in kernel or bad software updates.
Send to AitalMAC tech multiple pictures with all the content of the section Debug file information: from the LinuxCNC error window.
If the error is related to hm2_pci try to open the CNC controller, and unplug clean and plug back the CNC controller PCI card connected to LPT 1 connection, you will have to unscrew the port from outside and remove the small nuts.