Can a font become 'corrupted,' and how to replace?

UPDATE: IT'S A BUG IN WORD!
Thanks to all who answered.  I did reinstall/repair the system fonts, but that didn't do it.  However, I found what was corrupting the text, but have no idea why it was.

The captions below the pictures are in Text Boxes.  What I did was to position the text box below the picture, centering it and butting its top margin against the picture margin for a consistent look.  Then I selected the photo, held down Ctrl and also selected the text box, then went up to the ribbon and invoked the Group Objects command... for two reasons.  1) I wanted a common left/right margin for the two so that the body text of the .docx would be a constant distance for both; that is, a straight-line right margin for the body text.  2) I wanted to be sure that if I had to move a picture, the accompanying text box would move with it.

Well, that Group Objects command is what corrupted the text box text.  I didn't see the corruption until I had closed and reopened the .docx, and have the feeling that it might have reopened okay for a while, but finally succumbed to whatever ultimately broke with the two merged.  Here are screenshots of the very same area, first with the objects grouped, and then ungrouped:

What I don't understand is why the file, grouped and 'corrupted,' didn't show up garbled on another computer, or why another font didn't garble when substituted, including the boldface version of the same font.  But whatever happens when those are grouped, it's fixed now and I'm happy as the proverbial clam.