I have about 1500 mp3's - many from Kazaa -and I've only very recently experienced this problem and only with very popular titles. I strongly believe that the record companies are trying to undermine the reputation of Kazaa by sharing deliberately corrupted mp3's/wma's/etc. The solution that has worked for me has been to avoid downloading any file listed as being available from multiple users, instead choosing those listed to (say) just one username. I'm guessing that the record companies employees are posting versions of the same corrupt file, hence "60 users" of a given title? This problem is nothing to do with bitrates - just open a corrupt file in a good quality sound editor with intrinsic "ignore" values for variable bitrates and you'll still get that static screech.
