The guest is not installed yet. It is being installed. As in in progress.Did you check the qemu-agent box when you created the VM?
So the guest-agent is not installed yet if I understand correctly? Shutdown can only work correctly if the guest agent is installed and running. If you really want to stop the VM during the Windows install, just use the Stop option - this works regardless of guest agent and is somewhat equivalent to just pulling the plug of a physical machine.The guest is not installed yet. It is being installed. As in in progress.
ps aux | grep "/usr/bin/kvm -id <insert vmid here>"
kill -9 <process id>