Missing font used for Next > button

I am trying to fix a computer for a local Group Home. I
am having a hard time because the buttons (such as the
Next button, Cancel button, etc) are blank. The START
button in the lower left hand corner also does not have
any text. When by some chance I push the proper button,
and it goes to a screen where some buttons are not
allowed, I can read them because they are ghosted. I
assume there is some missing font.

Any idea what font is used on these buttons?
Thanks, Jim