Hey, I have this really wierd problem affecting my downloaded music

It seems like any music I've downloaded recently from KazAa (plz no bashing) tweaks out in the middle of the song, and its really annoying. Ill be listening for awhile, then it goes haywire, nothing sounding like the original song.

I dont believe its my sound card or its drivers; drivers are updated and older songs still work fine. I tested it on Winamp3 and Windows Media Player, with same results. I have all patches, no spyware (if that even matters), etc etc. Windows XP Home, Sound Blaster Audigy Xgamer card

Any ideas?