I've got a 2008 R2 DC that rebooted twice in almost exactly twelve hours apart. It did this morning at 4:02 am and today a 4:08 pm. Don't really see anything in the logs. Just a lot of warnings. See below. However those aren't new. I've never been able to solve it.
The only other error is a disk error, but that is caused by the external disks I have attached to a USB hub. This also is not a new error.
The driver detected a controller error on \Device\Harddisk3\DR3.
Any ideas on where to start looking?
Windows could not record the Resultant Set of Policy (RSoP) information for the Group Policy extension <Security>. Group Policy settings successfully applied to the computer or user; however, management tools may not report accurately.