I just bought a brand new thumb drive to record some music from my Yamaha DGX 660. It worked a couple of times, but then the thumb drive started to have a message saying "the drive is busy now." I deleted and re formatted the thumb drive, now I have message asking me to format the thumb drive. What's wrong? I've tried to format the thumb drive multiple times but still everytime I plug the thumb drive, the message is asking me to format it again. Sometimes, after I format the thumb drive the message says "the limit of media has been reached."