If you go in to the options, there is a button to test your microphone. If you activate that, the game will freeze. I haven't found any mic uses in the game yet, so it's not bad. On a related note, when the mic needs to be used in most other games, it will freeze there too.
I'm getting the same problem, at the screen where it says nintendo it says 'Unable to write data. Switch off the DS and reinsert the Game Card' and it's not the ROM file because I tried it with No$gba and it worked perfectly