Problems with Sansa Clip+

Managed to get the right firmware in. Thanks. But the player is still acting erratically. It freezes up all the time, for example when I disconnect it from my computer, and songs that I’ve dragged-and-dropped from my computer to the Clip don’t show up on the menu. When I hook up the Clip to the computer again and look at the Music directory, all the songs are gone. Any ideas?