A few years ago, maybe 4 or 5, I had a problem with a font. I tried for a couple of days to solve it, assuming, as I tend to do, that I was doing something wrong. As I recall it was not a situation that allowed me to just select a different font. Bottom line turned out to be that the problem rested within the font itself and just as I was ready to do something drastic Microsoft released a fix for the problem. Boy was I ticked. But as usual I learned a lesson.
The bottom line is that fonts can become damaged or corrupted just like any other file. This can cause problems up to and including prohibiting you from even opening a specific document in which the corrupted font is being used.
You can choose to validate fonts before you install them. Doing so won’t prevent problems down the road, but it will help ensure you are not installing problem files. You accomplish this using Font Book which has been included as part of your operating system since OS X 10.3.
The quickest way to find Font Book is to type font book in the Spotlight search field. It will probably appear on top and you just click on it in Spotlight to open it. You can also find it in the Applications folder.
Note: if you haven’t ever opened Font Book, select Font Book > Preferences and set your preferences for it just like you would for any other application.
Mountain Lion Font Book Preferences
Font’s already installed
Font book automatically validates a font when you install it. But you can also validate all the fonts you already have installed. You can do all of the fonts currently in your Font Book at once.
Launch Font Book, then from the Edit menu, choose Select All or select ⌘A from your keyboard.
Highlighted Fonts in Font Book
Font Book selects all the fonts in the Font column. Then from the File menu select Validate Fonts and Font Book will validate all your fonts and then give you a score. A white check mark on a solid green circle means the font appears to be OK. A black exclamation mark on a solid yellow circle means the font is a duplicate. A white “x” in a red circle means there’s a serious error and you should delete the font. To be on the safe side, you should consider deleting fonts with yellow icons, also.
Font’s not yet installed
If you are worried about installing a font set that you want to download from the internet or obtain from some other source you can validate before you ever install the set. Leave the font set on your computer, your desktop is the logical place.
Open Font Book, select Validate File from the File menu. Locate the new font on your computer and click once on the font’s name and then click the Open button. You can select all the individual fonts at once using Select All (⌘A) or validate one at a time by highlighting each one as you go.
Click the File menu and select Validate Fonts. Delete any bad fonts using the same method as noted above.
It’s not a bad idea to run a font validation every few months just to make sure everything is still running smoothly.