It is a codec pack from Kazaa, which includes a P2P program that, in the past, has been known to cause problems with spware, adware and, from downloaded files, with viruses. Kazaa now say they have cleaned up their act.
I would use a utility like GSpot (http://www.headbands.com/gspot/) to examine the file and see what audio codec you need, then look for that. I know that DivX Codecs are safe, but DivX is a video player from http://www.divx.com and the codecs are included in their free video player package, so I am not sure whether they would have the required audio codec for you. They should do though.
I have a problem with Windows Media Player 10. When I try to open an mp3 file it reports that I don't have the necessary codecs installed. I installed the K_Lite package recently to 'address' some issues in Windows Movie Maker. I'm at a loss. Please help!