Management Server shut down alone !!
Just for clarity, the hypervisor running your management VM is different from the hypervisor that you will use as a compute node within your cloud, correct?
There are a couple of places you can look, to determine why a VM shutdown. First I would look at you hypervisor logs to ensure that it didn't shut down the VM for some reason. Next, I would look in /var/log on the VM itself. Specifically, look at the "messages" file, or similar depending on timing. If you run `cd /var/log; ls -ltr messages*` you will get a list of messages files in date order. You can also look a the output of dmesg (maybe piped through less) but you will have to ignore the most recent boot messages, which will be at the end of the output.