I've tracked down a difference between Aquamacs 2.4, under which slime functions on OS X 10.6.8, and pre-test emacs 24.0.92: Under Aquamacs version 2.4: (open-network-stream "slime lisp" nil "127.0.0.1" 4005) #<process slime lisp<1>> Under Emacs.app 24.0.92 (9.0) Debugger entered--Lisp error: (wrong-type-argument bufferp nil) buffer-local-value(dbgp-buffer-process nil) open-network-stream("slime lisp" nil "127.0.0.1" 4005) eval((open-network-stream "slime lisp" nil "127.0.0.1" 4005) nil) eval-last-sexp-1(t) eval-last-sexp(t) eval-print-last-sexp() call-interactively(eval-print-last-sexp nil nil) recursive-edit() debug(error (wrong-type-argument bufferp nil)) buffer-local-value(dbgp-buffer-process nil) open-network-stream("slime lisp" nil "127.0.0.1" 4005) eval((open-network-stream "slime lisp" nil "127.0.0.1" 4005) nil) eval-last-sexp-1(t) eval-last-sexp(t) eval-print-last-sexp() call-interactively(eval-print-last-sexp nil nil) Cliff Wulfman cwulfman@Princeton.EDU<mailto:cwulfman@Princeton.EDU>