What is she using to log in? 
Could it be an issue of a stray lock being held on a file?

What happens if you reboot that workstation? Does the problem persist?

Is remotely the only way that she is accessing this workstation or does she also use it locally?

I don't think it is corruption you are seeing.  Upon closing, the Sage 100 desktop saves the launcher's last on screen coordinates to the launcher.json file in the folder so when it launches the next time, it is restored to the same size and position.  This is a common problem for people who work on laptops that are sometimes connected to more than one monitor.  If they closed Sage 100 on monitor 2, then disconnect the laptop and take it home and attempt to launch Sage 100, monitor 2 is no longer connected but the Sage 100 desktop still restores to the saved coordinates.  Deleting the launcher.json file will cause it to appear on the default monitor upon the next launch.

If it is just launching on the other missing monitor,

Open Sage

Hold shift, and right click on the sage icon on the taskbar,

Choose Restore or Maximize and it will pop to the right screen