A family of Microsoft word processing software products for creating web, email, and print documents.
Phillip gave you the solution, he did not tell you why.
Word does not read OS X's font list, it maintains its own, which it rebuilds from OS X's list, each time Word starts after a computer restart. Phillip's utility blows away both lists, so forcing both to rebuild.
My solution is "Don't use the Font Menu in Word." I never do. I customise Word's formatting styles for all the formats that I use. Each of these styles specifies a font. I never need to look at the font menu: I know that if the style name is right, all of the formatting (including the font...) for that paragraph is correct. I don't need to look: in fact, I don't display either the font name or the font size on my toolbar, because I never need to know it.
Realistically, I use only about 25 styles. I might create one or two specials for a particular document, but that's rare. Many of my fonts were set in 1989 and I have not looked at them since. With one exception: I changed all of Arial to Calibri when Calibri came out, because it's nicer on-screen :-)
Cheers