Many, many things these days rely heavily upon computer control - TVs, cars, dishwashers, airplanes, et al. The airplane is the one we are concerned with here. The FAA has issued a directive to carriers using the Boeing Dreamliner that they must reboot the aircraft flight systems at least once every three weeks, until a software issue is resolved.
Aircraft generally don't have a lot of downtime, unless they are actually being repaired, but industry insiders said it would probably be unusual for a passenger aircraft to be "on" for more than a week at a time. Nevertheless, the FAA is requiring this practice until the issue is resolved by Boeing engineers.