Have you tried playing the file with another audio player ? ( like
www.Winamp.com , which is much better for audio anyway).
Also update your codecs with the Nimo Codec package here :
http://nimo.everwicked.com/
After installing that and you still can't play the mp3 with winamp or windows media player, the file may be corrupt.
Try downloading an mp3 that has many sources ( for example 10+) if possible and see if you still have the problem with that file.
Good luck