no audio playback

On several files, some of which I encoded myself so I am dead sure I have the proper codec, BS player will fail to play the audio at all or will repeat the first tenth of a second of audio on an interval. I have several different versions of BS player including the latest and greatest. The files play fine in DivX player but, as I prefer BS Player, would like to know what is causing the difference. The same files run fine on my friend's computer who has an almost identical setup with the same sound card, Game Theater XP. According the GSpot I have 3 compatible codecs installed so any ideas as to why it's not working? Sorry if this has been broached before. Much appreciated.