I was having some issues with OnecncXP shutting down unexpectedly, and I thought it was some kind of corruption of my xfa file, however, the exact same file would run ok on another computer. Even the same troubled file would suddenly begin working a couple of days later on the original computer where it was made!
It turned out that I had patched the last release of OnecncXP over top of my earlier first installation, and this seemed to cause a registry glitch that was duplicating the file locations. I think this was causing the crash.
You can check the status of your Onecnc registry settings by running regedit, looking under HKEY_CURRENT_USER | SOFTWARE | OneCNC-XP Software | C: (or other drive) | ONECNC~1
If you see two instances of ONECNC-XP below or after the drive letter, you may experience this problem.
Solution: uninstall completely, check through and remove the Onecnc-XP keys from the registry and re-install. Also, before you do anything, back up your customized *.bin files and posts from the settings folder, and also your personal subfolder (if other than default) under the user folder.