ChromeOS version: 66.0.3359.203 
Cfm device model: guado
Case#: 16280688

Description:
CfM devices (using MIMO screen) suddenly show a white screen and become unresponsive to a reset. A reboot from the admin Console does not resolve the issue, but full CfM shutdown does resolves it temporarily.  This seems to happen while the device is idle and users notice it when they go into the meeting room. 



Steps to reproduce:
1. Leave CFM for some time

Current Behavior / Reproduction: 
CFM crashes

Expected Behavior: 
CFM works

Drive link to logs: 
MIMO screen - https://drive.google.com/file/d/1zPOfY9_EJyjzFwBKfv1lYEJlJhM-hj-q/view?usp=sharing
TV screen - 
https://drive.google.com/file/d/1s-XLujIs_gD_laSjgqog9kAufGS5OPBU/view?usp=sharing

HAMSCX001680 - Issue was noticed on 7/10/2018 at 12:40PM Pacific Time. Debug logs: 
https://drive.google.com/file/d/1J6S652JB66wbROp0RHeswk9YG9zd60ZW/view?usp=sharing
HAMSCX001948 - Issue was noticed on 7/11/2018 at 10:20AM Pacific Time. Debug logs: 
https://drive.google.com/file/d/1cG8ZUIkH8M4V3vidI4Ot555cBsezlLc0/view?usp=sharing


I have similar report from 68.0.3440.40 in another case, #16325977, but waiting to debug logs there. For them issue seems to happening during calls too.