Not being able to see it, I would ask her if she had uninstalled any of the fonts. Does other text on the system look normal?
If not that, perhaps a change was made to one of the display settings. Right click the Desktop then go to Personalize, then Display in lower left. Perhaps changing that setting, or adjusting the "Set custom text size (DPI)" might help.
Edit: There is one more place, right click desktop and select Personalize. Then "Window Color" on the bottom middle. The "Advanced appearance settings..." may allow you to change the font in a specific type of dialog window.