Dave, FWIW, I also ran into this one: http://article.gmane.org/gmane.comp.lang.smalltalk.squeak.general/121000/mat... Is there a time when a user/programmer would want to send #close rather than #closePipes? Perhaps #close could become #basicClose with #close then being changed to send #closePipes. #closePipes seems like something that might be private; it's (almost) obvious now, but it looks like a recurring trap for casual users. It appears that I had been having intermittent problems with this for a while. Yesterday, I ran a big batch that would not go to completion, and I noted that after the first error, pretty much every file operation failed. The latter lead me to strongly suspect cleanup of the pipes, and the above was then easy to find. The batch runs nicely now. Bill