CCR - reboot kernel failure

Hi,
we got this CCR1036-12G-4S runing V6.38 software

Its reboots sometimes itself:
Getting this from log

jan/01/1970 02:00:14 system,error,critical router was rebooted without proper shutdown, probably kernel failure
03:31:18 system,error,critical kernel failure in previous boot

Has anyone same experience as me

Please take a look at this post:
http://forum.mikrotik.com/t/random-kernel-failure-in-previous-boot-log/111511/1