For MP3 playback I use WINAMP. It's free and not as big an application.
Sorry, WMP seems to break and repair is less than assured.
I've tried several different mp3's and both are not recognized in My Computer as a drive nor do they appear in Media Player. I get "device not found" in Media Player. I've got Media Player 10 and XP. I've tried many possible solutions and none work. Help please!