In Emacs 20.7 running under Debian GNU/linux `testing' (kernel version 2.4.6), I have an intermittent but annoying problem.
Under two kinds of circumstance, I get the generic and mysterious error-message: Wrong type argument: number-or-marker-p, (+ -4) This happens (i) when I try to do filename completion with `visit-file' or `dired' or (ii) when I call `switch-to-buffer-in-another-frame' (C-x 5 b). It happens only occasionally, though, and I can always fix it by exiting the emacs session and restarting. I don't know how to reproduce the behaviour reliably, but I can be sure that it will happen ultimately if the emacs session is long enough. Does anyone know how I might trace this problem to its origins? Or solve it? Thanks very much in advance, Jim