That's a typical response from WMP when it doesn't have the correct codec to play a particular file (audio/video.) There's different types of mp3's out there & some require special codecs to play. You'll need to obtain these xtra codecs. Also there's mp4 (m4a) which is a new type of format that's showing up. WMP will not play these. Winamp 5.02, Apple iTunes, Compaact!, Nero 6, dBpowerAMP, Foobar2000 are audio/burner apps that have the ability to play m4a files. In summary, I'd suggest you obtain xtra codecs for WMP or/& get a hold of xtra audio app (WinAmp is good.)