if you are running retrofw 2.0 you need to reflash your sd card. First you need to destroy all partitions on the sdcard, then create a new one in fat32. Then flash the retrofw 2.0 image. I know this is a pain in the ass and sounds goofy but that's what i had to do and it worked. otherwise the file structure somehow gets goofed. If you are running firmware 1.2 i have zero idea.