I've had this issue on several different computers since Facebook Graal came out, so I guess it's time I posted something about it.
Every now and then, the Facebook App will "break" for a few days to a week. During this time it will be completely broken. Instead of displaying the actual game as it should, it merely loads and then displays a solid black screen. (The background music does, however, continue to play.)
After a few days to a week, the problem resolves itself and then starts working again.
Has anybody else had this issue or similar?