Comment 8 for bug 1194834

I often reboot overnight, so quite likely that happened - though it's not rare so it can't be *just* that.

I'm fairly sure I didn't use the Tweak tool before it happened.

Yes, I understand this is difficult to debug, but I think there's value in keeping track of it here.

I wonder when the tweak tool was most recently updated, or perhaps something to do with some other package/tool that gets updated.