UserAgent: Mozilla/5.0 (X11; CrOS aarch64 9765.48.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.70 Safari/537.36
Platform: 9765.48.0 (Official Build) beta-channel kevin

Steps to reproduce the problem:
1. Use chromebook

What is the expected behavior?
No unintended reboots..

What went wrong?
System reboots quite often, more than 10 times a day on average, sometimes even that many times within a single hour. 

There is also a tendency for full screen android apps to freeze. When that happens (and if there is not a reboot at that time), showing running apps and closing from that screen fixes the issue.

Did this work before? Yes Two updates ago.

Chrome version: 61.0.3163.70  Channel: beta
OS Version: 9765.48.0
Flash Version: Shockwave Flash 27.0 r0

Device is a Samsung Chromebook Plus.