So I recently got an r4 SDHC DS card and it works fine but there is a problem that I have run into when I add files. When I first got the card I put about 3GB of files on it, all at the same time. They all read correctly. However, whenever I add a new file, rom, mp3, video, or something else. It cannot read it and says that it is corrupted. When I look at it with the file viewer it reads something like (SDG234ewfr#T%EWGTg) and so on. What did I do wrong?