In latest CVS emacs, try to send a bug report from the Help Menu, enter text
for "Bug Subject: " and Emacs.app hangs.

GNU Emacs 23.0.91.1 (i386-apple-darwin9.6.0, NS apple-appkit-949.43)
 of 2009-03-13 on phi-qp617070u2s.Princeton.EDU

Mac OS 10.5.6.

 Gil Harman