I’m posting this in hopes of saving other screenwriters a few hours of potential frustration with Final Draft. After installing the OS X version, or upgrading your system software, or sometimes for no discernible reason at all, Final Draft will occasionally refuse to open. It bounces one or twice in the dock, then quits. Sometimes it gives you a message; other times it doesn’t.
Obviously, you can go through the help forums at Final Draft to look for an answer, but if you’re using the OS X version for Mac, first check for one specific thing: a corrupted font file.
In the “Fonts” folder of your account’s “Library” folder (that is, John/Library/Fonts, rather than the main system-wide Library) look for the file “Courier Final Draft.” (Confused? Click the thumbnail to show you where to find this file.)
Drag the “Courier Final Draft” file to the trash. Log out, then log back in. Try to launch Final Draft. If it works, problem solved. Go to the website to download a non-corrupted version of Courier Final Draft, and put it in the main library’s fonts folder.
If that doesn’t work, make sure you’ve updated to the most recent version of Final Draft, then start digging through the support forums.