Some more info on this case (anybody out there with Solaris and Forte 6.2 more familiar with the Perl guts than I am?) * the same failures (signal handling!) happen with optimization (-O) switched off, and with debugging enabled (-g) * these failures do NOT occur when compiled with gcc-3.3 and the rest of the environment unchanged This makes me believe that Sun's Forte 6.2 compiler is the culprit - but it compiled 5.8.0 with the same options ok. So there seems to be a change near the signal handling code in Perl 5.8.1 that triggers a bug in Forte, or the change itself relies on some property of gcc that confuses Forte.