Hey, all -
Tomorrow is the second Tuesday of the month, the day Microsoft releases Windows updates. If your machine is configured to automatically download and install updates, this may result in an automatic reboot. If you are rendering at the time you will lose your work!!
So - anyone rendering overnight or unattended between now and about this time tomorrow- make sure your machine is NOT configured to automatically download and install Windows updates!!
I... errr... won't mention why this happens to be fresh in my mind this month...