I had this problem too, and found a solution here.
This is the relevent excerpt:
1) Restart your Mac and immediately hold down the Shift key when you hear the startup chime to boot into Safe Mode. Keep holding the Shift key until OS X asks you to log in (you will get this screen on a Safe Mode boot even if your Mac is set to automatically log in). Let the Mac finish booting to the desktop and then restart normally. This will clear Font Book's database and the cache files for the user account you logged into in Safe Mode.
In Leopard or earlier, any font sets you have created will be gone. Also, all fonts in the three main Fonts folders (System, Library, your user account) will now be active, regardless of their state beforehand.
Close all running applications. From an administrator account, open the Terminal app and enter the following command (or copy/paste it from here):
sudo atsutil databases -remove
This removes all font cache files maintained by OS X. Both for the system and the active user account. After running the command, close Terminal and immediately restart your Mac.
Tried it. It worked. Hope this helps.