Try reformatting the SD card.My twilight menu++ keeps getting this error everytime I start it up. "fatinitDefault failed!"
Well, yes, it used to work just fine for quite a while. I suddenly got this error yesterday. Actually, at first it was just freezing during the first loading screen. Then I tried updating it and now it shows that error message. The last thing I did before this issue began was browsing through the setting menu and changing whether the last game played would be the one that appears on the upper part of the screen right after you start the app. Oh, and before that, I was playing Pokemon Mystery Dungeon: Explorers of Sky.
If that doesn't fix it, try another SD card.