Just a quick note to anyone out there running Hyper-V in a cluster situation. We seemed to have a strange issue where occasionally when we Live Migrated a Virtual Machine from one host to another, the host that the VM was being migrated from would crash. After banging my head against the wall repeatedly, and then checking and re-checking my cluster configuration, I ran across this TechNet Forum thread: http://bit.ly/vmcrash. Basically, it seems that there is now a known issue with Windows Server 2008 R2 and some newer AMD processors. We’ve got dual quad core Opterons in each of our cluster nodes, and this seems to be exactly the problem we were experiencing. The hotfix is not publicly available yet, but if you call Microsoft product support and mention KB 981618, they should be able to get you the current hotfix. I installed it on all three of our nodes, and it seems to have resolved the issue for us.