> Mark, did your initial backtrace look like this:
No; the segfault was definitely happening in delwin rather than putwin. But I did see something like your backtrace when I tried to use ncurses from ports (installed in /usr/local) rather than the system ncurses. This was all on FreeBSD 8.0/amd64, by the way, running in a VM on Parallels. I got the same results both when working directly within the VM terminal, and when ssh'ing to the VM from an OS X Terminal.
Maybe running this through Valgrind or something similar might show what's going on. (Though it's not clear from a quick google whether Valgrind works on FreeBSD.)