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