I ran your patch several times and it takes a while to happen, but it still buzzes eventually (although once it happened on the third or fourth load). I recorded the results here: http://www.4thharmonic.com/audio/readanysf~test2.mp3 - (the buzz happens around 2:28 and happens 3 times)
ok, this smells like a memory leak to me. Not going to be easy to find.
Do you have other externals loaded at the same time? If so, try re-running my stress patch with no other libs or externals loaded.
thanks -august.