Did your AD jump back to the year 2000 during the past weekend? .. This could have happened if you are syncing your time with the USNO.NAVY.MIL, as they apparently had a disruption on the 19th. see
But if time jumped back on your AD, you’re in trouble.. and the way to get out of it? take a cup of coffee, do NOT reboot anything yet.. and read the extensive blogpost ..