I'm thinking it's not genuine but my own mem stick works fine. I'm working on my friend's by the way. When it is on his psp, on mem stick, it showed a lot of corrupted data icons and also on video and music. i tried to format the mem stick on the psp but still does the same thing. i formatted the mem stick on my computer, showed that there is some space on it, but when i tried to plug it back in the psp and reformat it there, it still does the same thing. can anyone help? oh, i isolated the issue by trying my own mem stick on his psp and it works fine, meaning the firmware is not the problem. help pls?