Fixing the Font Cache with the 10.6.8 Update
If, like me, you had font problems after applying Apple’s Mac OS X 10.6.8 Update, there’s a simple solution: delete the font cache. You can easily delete the font cache by using the free tool OnyX—which also does much else besides.
For me, the issue became clear when I went to look at a job in Adobe Illustrator. Opening the file should have triggered Extensis Suitcase Fusion to load a particular font, but it didn’t. In fact, none of my fonts could be previewed in Fusion: instead was a note stating “Font Unavailable”. Once I deleted the font cache & restarted, everything was fine.