another backtrace, now with a little more detail.
seems like the remote side times out, or some firewall gets bored due to a slow traffic and closes the connection. the problem only comes after the print-object method of the socket starts saying "unconnected" and we try to call close on the socket then.
then the attached backtrace comes and the lisp vm is dead after that.
it's also strange that write-sequence happily returns with success to the unconnected socket.
hth,