Weirdness

I took that stupid Twilight book off my MP3 player today and put a real vampire book on it. Then I noticed that no matter where I looked, on the player itself or on the micro SD card, I couldn't find the book I'm listening to now. I was afraid that I had somehow accidentally deleted it, too. Nope, when I unplugged the player from the computer and looked at the player itself, my book was still there. Which is good, since I'm listening to it.

Tonight I hooked the player up again and added some music, and still can't find that book. It's still there. It still plays, but the computer can't see it. There's another book on there that I've already listened to and would delete, except it's invisible, too. Really, this makes no sense.