"Stephen J. Turnbull" wrote: I might also have corrupt sources, but I doubt it (as a build for Linux from the same source tree works fine). In any case I have the very same error with 21.5.13 on AIX 5.1. Here's my backtrace (similar to Rick's): Signaling: (void-variable region) zmacs-make-extent-for-region((#<marker at 387 in init.el 0x2039640c> . #<marker at 387 in init.el 0x20396424>)) zmacs-activate-region() push-mark(nil nil t) set-mark-command(nil) call-interactively(set-mark-command) command-execute(set-mark-command t) execute-extended-command(nil) call-interactively(execute-extended-command) -- Markus Alt IBM Lab Boeblingen, Germany altmark(a)de.ibm.com