[ovirt-users] VM's gone to unknown state

Hello, I have an issue with ovirt 4.3 console. The exact issue is, except hosted engine, all other VM's gone to unknown state. I wonder what's the problem is? And how bring back the VM's to normal state. I can see that nothing is enable (for instance, acktivate option, maintaiance option, etc). Can anyone guide me please in this? Thanks in advance! Best Regards, Hariharan