[CentOS] Still a kvm problem after 5.6 upgrade

After the upgrade, my VMs stopped loading. Found others with the problem
and followed the guidance to use virsh to dump the xml file of the VM,
undefine the VM, edit the xml file to change 'raw' to 'qcow2', redefine
the VM from the edited xml, and restart the machine.  I still get the
following error when I try to start the VM:

redlibvirtError: internal error Process exited while reading console log
output: qemu: could not open disk image /dev/hda

A libvirt update came in last night, so I was hoping the update would
allow libvirt to automatically recognize the type of image file (as
previous versions did).  Nope.

Any other thoughts?

Dave M