Comment 20 for bug 446395

This seems to be because gnome-screensaver-dialog exits after the 5th failed attempt, whilst the main gnome-screensaver process is still shaking the dialog to indicate an auth failure. I've ran it through xtrace which shows that gnome-screensaver tries to do some X calls on the gnome-screensaver-dialog window after it was destroyed. I also rebuilt gnome-screensaver with some extra debug statements which show that gnome-screensaver-dialog exits whilst the dialog is being shaken. This happens every time, but it just seems to be that you need to be unlucky with the timing to get it to crash.

Anyway, the current implementation is not robust and is race-prone, so I will work on fixing that now.