何もしてないのにある日突然こんなエラーが出てnavi2chが動かなくなった・・・？

Debugger entered--Lisp error: (args-out-of-range 1 18)
put-text-property(1 18 fontified t)
jit-lock-force-redisplay(#<buffer *Echo Area 0*> 1 18)
apply(jit-lock-force-redisplay (#<buffer *Echo Area 0*> 1 18))
timer-event-handler([t 20740 63187 668904 nil jit-lock-force-redisplay (#<buffer *Echo Area 0*> 1 18) nil 731000])
accept-process-output(#<process navi2ch connection>)
navi2ch-net-get-status(#<process navi2ch connection>)
navi2ch-net-download-file("http://menu.2ch.net/bbsmenu.html"; "Fri, 11 Jan 2013 17:12:02 GMT" ("200" "304" nil) nil)
navi2ch-list-sync(nil t)
navi2ch-list()
navi2ch(nil)
call-interactively(navi2ch record nil)
command-execute(navi2ch record)
execute-extended-command(nil "navi2ch")
call-interactively(execute-extended-command nil nil)