Edge 1040 multiple crashes since 28.20

First ride since the firmwide update - navigating a course, about 60 miles. 

Device crashed 3 or 4 times within the first hour - says it is 'saving diagnostics' or something, then reboots. After reboot it resumes the course navigation.

It wasn't doing this before this latest update.

I gave up the course after an hour or so due to this problem.