VMs shut themselves down

Hello Team, I have an openstack environment with 4 compute Nodes however yesterday out of the blue, the Instances on one of the compute nodes started shutting themselves down. Then I realized the the compute service was disabled when I checked in Horizon. I enabled it and restarted the instances and all was well but I cant figure out what caused it. I have attached the nova_compute logs here incase someone would like to support https://paste.openstack.org/show/bxqpgjvqT3DlOYWoeejc/ Regards Tony Karera