I've been noticing the background timer giving odd messages from emacs-w32 once in a while such as the following when not touching the keyboard and the editor is idle.:
seconds-to-time: Arithmetic range error: "round", -0.0e+NaN seconds-to-time: Arithmetic range error: "round", 0.0 The stack dump of a recent emacs crash report on this list seemed to be in background timer code. Maybe we found something.