I did just find this:
http://www.gossamer-threads.com/lists/interchange/users/38451
...which advises this:
> Edit this file: /path/to/interchange/bin/interchange
> and make the second line read:
> $ENV{PERL_SIGNALS} = "unsafe";
That got rid of the warning message when I restart IC, but breadcrumbs
still isn't working. sigh.
Bob