[libvirt] vms hung

Hello, I am running libvirt-2.0.0-10.el7_3.2.x86_64 on CentOS 7.3, I have few vms of CentOS and Windows 2012 servers. Randomly they are hung, but the status of virtual machine keep running, vnc and network not responding. I have checked all /var/log/messages and /var/log/libvirt/qemu/vm.log but nothing found anything wrong. Would you please help what should I do more so I can find the issue. -- Umar