Last year we bought (2) R4 upgrade revolution for DS – V1-4 (NDSi LL(XL)/NDSI/NDSL/NDS). I have a SanDisk 2GB micro memory card. I have approximately 30 or more DSi games on it. My sons have been playing them on their DSi for almost a year now. One day one of my son’s DSi stop letting him get in the game to play, saying error . . . A week later my other son’s DSi said the same thing. Do you know what is going on? Why have they been able to play them for almost a year and now within a week’s time they both stop?