This repeatedly freezes the whole machine (a G5 quad), needing a power reboot.
Welcome to Clozure Common Lisp Version 1.2-r9226-RC1 (DarwinPPC32)!
? (defun stress-test ()
(loop for n from 1 do
(process-run-function (format nil "Stress ~D" n)
#'(lambda () (loop do (1+ 1))))))
STRESS-TEST
? (stress-test)