System.IO.FileNotFoundException

The question is too short to understand. Is your application trying to open a file or reading something from any file. While you running the application on the other machine, that file may be missing.

the exception clearly indicates that the file which the application is trying to access is not found at the location specified.
try to add break points and debug the application

more details will be useful for us to understand the issue

Is the same with release version of the program?

Remember also that if the user has no rights to read the file it's not visible for the program.

See screenshot of UI. Each button launches a .bat, vbs, or exe file contained in folder C:\Scripts. It does not however read/write from file system at launch - not until a button is clicked. But this error prevents app from even launching.

application.bmp

Also as I mentioned before, no point in debugging as it runs and functions fine on dev machine.

Probably .NET is unable to seek a required file. Does the second machine has administrative rights?

I have tried on multiple machines. If you are asking am I logged on as administrator on other machines, yes.

You were, I was missing a third party library.
Thanks!