a) Running Windows Server 2012 Hyper-V – Cluster
b) Encountered problem as listed in this post. You have repair the CNO but the problem keep coming back. When this problem occurred, you cannot perform live migrate except Repair. Temporally this will solve the problem but this incident will keep appearing.
This incident happened due to password syncronization issue. To solve it, apply hotfix KB 2838043. Click here to get the hotfix and more detail on other issue that this fix apply for.