So I found my old DSi, and much to my surprise it had Sudoku on it and was running firmware version 1.4U. I exported Sudoku to an SD card, applied the patch from hackmii, but when I try to copy the patched file back to system memory I get a message "This software cannot be copied." Any idea what could be causing this? I have repeatedly checked my firmware version in the settings screen and confirmed that I'm running 1.4U, which should be low enough for sudokuhax to work. From what I can gather, it was the 1.4.2 update which prevented copying sudokuhax to internal memory... So everything should work on 1.4U.