The LW Player doesn't work very well. Disable it by going to Tools>Options>Player(in LW), untick the box and click apply.
Now try launching a song and it will open in your default player(probably WMP). If it plays ok, then problem solved. If it still won't play, try a different player.
VLC media player is a good one that will play most any media file.
For more info, see this sticky:
CODECs list for Movies/Alternate players / Video help forums/ video-mp3 fixers