Eh? That's strange. It's working fine in 480p mode for me, but I'm sure that isn't what you wanted to hear. You say it is simply showing a black screen at boot with 480p enabled?
Did you try disabling the other modes as well? For some reason, 007-EoN had major issues with 1080i or 720p were enabled in the dashboard, so you had to disable those two options in order to use regular 480p mode. I can't imagine that kind of glitch slipping through in Fable, though...
What kind of TV do you have?