can't see imported mp3s in file manager

[Jabberwocky]

I used doubletwist and windows media player to transfer my music over to droid, and aside from having to recreate a few playlists, was very happy. I then tried to add album art that I had not had before and noticed that in astro, the only file that actually contained playable files was one I had purchased from the Amazon mp3 store and the rest were a collection of m4a and wma files and wouldn't play. However, when I look at music in the music application, its all there in mp3 and plays properly. Anyone knows what happened and how to fix it?