I have driven my ' 01 GS300 for over 3 years and this never happeend to me until recently. IT happed once and ever repeated so I dint bother investigating it. It happed when I took a trip to Vegas from CHicago. I was fine in the 120 F heat it was fine in the Colorado Mountains on the highest road in the world....but when I got to Grand Canyon....I rebooted. (The screen got garbeled..it forze for a second and went back to Lexus screen) All route data was lost so i had to reporgram it.
It was yearly morning, the tempreature was 70 F and the car cooled overnight. Maybe it was some kind of magnetic storm or some geomagnetic disturbance due to a solar flare...I dont know... the car ran fine.