When the BB is connected to your PC, can you view the contents of the media card?
When you got to Options > Media Card, what settings do you have?
Also.... are the songs from iTunes? How did you convert them? If you converted them with Roxio, that may not remove the DRM. One way to remove the DRM protection is to burn the songs to a cd, then rip them again to your PC. Then they will play on any mp3 player.