It would seem to me the ECU is locking up based on your desciption that a reboot fixes it. Electrical gremlins can be caused by nearly anything from a loose connection to a major ECU failure.
25 years ago, I had a repeating fault in the local control console of my main propulsion engines on the destroyer I was stationed on (USS Kidd, DDG 993). We troubleshot that thing for days and had absolutely no idea were to go next.
By chance the ship took a minor manuvering roll and I happened to be looking in exactly the right place and precisely the right time, with a guy standing next to me blocking the overhead lighting. I saw what appeared to be an arc on a stack of printed circuit boards. I looked closer and found a tiny 3/32 screw that had dislodged from someplace rolling between the PCB and the grounded frame.