PPS: I just checked, and the binary for the 'ls' command is what's called 'pure code'; i.e. the instructions are in a separate (potentially shared) block of memory from the process' data (un-shared). I don't recall off the top of my head whether the location of that shared block of memory is in the per-process swappable kernel data (which is included in the process core dump). I'll check tomorrow, when I'm not sick as a dog (pretty miserable right at the moment). It would be east to mod the OS to print all that info when that illegal instruction trap happens - but that will change the size of the OS, so will probably change the location the process is at; so that might cause the symptoms to change. Ditto for recompilling 'ls' to make it a unified blob. :-) Don't worry, we'll nail it! Noel