When I left for work this morning, my S was operating normally. I drove about 5 miles and then stopped at a store for about 5 minutes, and when I got back into the car, I received a warning message "Driver Assistance features unavailable. If the problem persists, contact Tesla Service". Sure enough, neither cruise control nor Autopilot would work. I rebooted to no avail, although I did not turn off the power to the car. I wondered if Tesla had disabled the Driver Assistance features, as some on here have feared. I drove another couple of miles with the warning message on, and then stopped at another store for about 5 minutes. When I got back into the car, the message was gone and everything functioned properly. We have had no recent firmware updates. Has anyone else had this problem?