and, i can confirm. trainer not working with latest version of Fable 3, for some reason. its weird, the trainer launches just fine, the options just wot activate.
the things i tried were
1. unblocking the file - anything windows 8 and above will block or immediately delete files from unknown sources. have to right click the file and open properties and unblock it.
2. tried launching before game and after game.
3. tried activating trainer options with game up and with game minimized.
i have windows 8. and the steam edition of the game. and yes, the game was an epic pita to get working. had to do the GFWL work around by downloading the live file. so not sure if thats effecting it.