Hello I am having a problem with my micro SD card. I load the first video on it, which is the proper format, and it will play. But any video I load after it, it will not play and when I try it on my nook it get an error message saying sorry the file can't be played. I think there is something wrong when I transfer the movies from my Mac to the Micro SD card. It's not the movie format because it doesn't matter which movie I put in first. If anyone can help, I'd appreciate it. It's a class 4 by the way.