on both host and guest running CentOS 6.3 with KVM/Qemu virtualization, I have the following scenarios:

1. "virsh shutdown kvm1" did not shutdown at all. virsh lists guest as running.
2. "service libvirt-guests stop" did not shutdown in 280 seconds (shutdown_timeout=300. on_shutdown=shutdown)
3. "shutdown now" from within guest, guest becomes unreachable. virsh lists guest as running, though it could not connect to it.
4. "shutdown -h now" from within guest works.
5. "shutdown -r now" from within guest works.

Libvirt logs show nothing for the first 3 scenarios. I can pause the guest fine.

Bottom line, I cannot shutdown from outside the guest. What do I check to figure out what is going on?