Så här skriver Apple i sitt dokument Advanced Typography with Mac OS X som de publicerade när Jaguar dök upp.
Font Corruption
In Mac OS 9,if two fonts had the same internal ID
number,the Mac OS renumbered one of them
to avoid conflicts.As a result,sometimes a font
file became corrupted,triggering application and
system crashes.
Mac OS X doesn’t try to alter fonts,so the chances
of a font file becoming corrupted are almost nonex-
istent.This doesn’t mean that there are no longer
corrupt fonts.Legacy fonts from earlier systems
and fonts purchased from nonstandard vendors
can still cause problems.
Insider Software, de som gör FontAgent skriver på sin sida;
So what makes a font go bad?
What makes an otherwise normal, upstanding font turn to the dark side? System crashes. disk problems. OS upgrades. file allocation table problems to name a few ways. Without a doubt, any file that is open during a system or application crash is subject to corruption, and since some or all of your font files are always open, they are easy targets for being damaged without you ever knowing it! When fonts become corrupt, they make big trouble for your system. Sometimes corrupt fonts make their presence known by causing sluggish performance while the OS tries to figure out what's going on. Sometimes they cause applications to freeze up, so you lose all your work. And sometimes they cause your entire system to crash, resulting in further font corruption.
Do you have corrupt fonts?
If you have owned your fonts for a while, the chances of your having font corruption problems are very high. Even if your fonts are new, it takes only one glitch in a single font file to bring your applications crashing down around you. Why take that chance when you can use FontAgent® Pro to thoroughly verify the integrity of all your fonts?
Creative Pro skrev det här i en artikel om Mac OS X;
Claim 3: Mac OS X corrupts fonts.
This is also false. One of the great things about Mac OS X is that it opens fonts read-only, unlike previous systems which sometimes opened them read-write, which meant that there was a small (but non-zero) possibility that they would become corrupt if the system crashed while the font was open.