jkoebel,
If you're referencing the NPM in the Engineer's Toolset, it is writing to an MS Access file and when the tool is open and is being written to, a lock file will also be produced in the directory so that you can not edit, open or manage that file. If you want to back up the file, you'll need to close the application.
Thanks,
Jason HensonLoop1 Systemshttp://www.loop1systems.com/