I checked my fonts with FontBook and I found that many of them, though they worked, had validation issues. So I thought I'd search for a program to try and repair them and I dowloaded this.

The program ran fine: it checked fonts, found problems and fixed them. It found problems in fonts that FontBook hadn't apparently noticed, but on the other side it didn't find any problems in the ones FontBook had pointed as bad.

After everything was done, I opened FontBook and found out that my fonts had suddenly decreased........ Now half of my user fonts (60+) DON'T work anymore though they appear as "installed". They don't even show up in FontBook!!!

I guess now I'll have to check which fonts have been modified by FontDoctor and replace them with the ones from a recent backup (which I luckily have...)..

Mind, I'm *not* saying this program is rubbish. It does have some positive reviews, so I guess it's just a matter of luck and/or what kind of fonts you have installed. Just to be sure, I'd suggest you to do a backup of your fonts, so that you can revert to it in case the program screws something up. :(