I have had a several gig-sized collection of non-drm music files on my droid for several months - and have had no problems playing them. They were all saved under a generic "music" file on my sd card. Most are .M4a files. Tonight I downloaded some mp3s from Amazon's MP3 store. After the new songs from Amazon downloaded, they showed and played in music player but none of the previous files appeared in the player. I manually copied the new Amazon files to my generic music file and deleted the Amazon file from my sd card. Now both the original music files and the new Amazon files show up, but only the original files play. The Amazon files say they are not supported by the player. Any ideas? I'm thinking there is a conflict between the two file types? Thanks!!!