Pre-flight is showing an error. When I drill down the tree it comes to a single, blank character formatted with the missing font, on a blank, three-column page that I made to hold an index. I looked at the master page, and there is no content visible there. Currently my index consists of two, 3-col pages, but there is only one pre-flight error.
This may have been induced as I made a series of character color changes in paragraph styles. Is there a way of searching all font settings to see if one of them is "missing", so that I can change it?
Go to Type > Find Font, and it will show you all the fonts in your document. If you select the font, and click the More Info button, it will tell you a lot about how many characters and styles the font is used on. You can also use the Find button to find individual instances.