In the office today, we found a very frustrating bug with Flash CS5 (on Apple OSX, at least) involving runtime shared font libraries. There was an inconsistency between two of our computers, mine and my developer co-worker, in which publishing a library FLA would cause fonts to either work or not work. Theoretically, there should not have been any font-related differences between us because the fonts were being pulled from another file, but it was very clear that his publishes worked and mine did not.
We figured this was either corruption in the FLA, corruption in the fonts, or Flash was bugging out in some manner. What we found was that regardless of whether or not you’re actually embedding glyphs, Flash still takes takes your system fonts into account when publishing. So the difference between my co-worker’s computer and mine was that he had uninstalled the site’s fonts before running Flash and publishing while I had not.
So what’s the fix? You have to disable or uninstall whatever fonts you are loading in via runtime before publishing any file that references them.
Now whether this applies to all cases is unknown at this point, but it is a real problem in this project and possibly with the method of implementation we use.
For your reference, this is the basic framework we used for our runtime font loading.