radio/navigation/apps system restarts intermittently

I purchased my Avalon April 30, 2015. June 7, 2015 I had my first experience with the radio/navigation/apps system shutting down and rebooting while driving. It occurred again intermittently about 3 times throughout the year of 2015. It continued throughout 2016, but happening more frequently. On July 31 I thought the system had crashed and gone out for good. I was traveling using the navigation system, and took an incoming cell call and upon completing the call (which lasted maybe 1 minute), the phone never disconnected within the system. The screen froze with the caller ID information displayed. The system would not respond to touch screen commands nor the power button. I had to pull over and turn the car off and back on. The system came up and I continued on my way for about 20 minutes when the system shut itself down again. This time it attempted to reset itself several times with no results (the start up screen kept reappearing). Again I had to pull over and turn the car off. I sat for a few minutes (as I needed the navigation system to get me to my destination). I cranked the car and it took an unusual amount of time to start the system. When it finally came up I was able to continue my journey. I see this issue is also occurring on the Highlander. THIS NEEDS TO BE CORRECTED.