Our Distiller Server (Solaris 10) has suddenly started emitting "distill termination status = 18" whenever we try to distill a postcript job to PDF. Distiller is getting called from a production script. If we attempt to distill the job by hand, it works correctly. I have been unable to find any reference for these error codes anywhere (Adobe kb or otherwise).
Just in case anybody has a similar problem, we discovered the solution. Apparently, one or more files in the .Acro* directory (either in the home directory or root, depending on how you are running Distiller) become corrupted. Removing this directory and re-running Distiller recreates the directory and all needed files.