Comment 9 for bug 904627

Found a very strange workaround.

In this example the VM name is VZ02-zentyal

To reproduce:
1) save a copy of /etc/libvirt/qemu/VZ02-zentyal.xml
2) edit this file with sudo virsh edit VZ02-zentyal
3) add in the device stanza this definition (taken from a VM created with Kubuntu 11.04)

    <disk type='block' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <target dev='hdc' bus='ide'/>
      <readonly/>
      <address type='drive' controller='0' bus='1' unit='0'/>
    </disk>
    <controller type='ide' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
    </controller>

4) reboot the VM -- ATTENTION now virt-manager crashes
5) reboot the host system
6) restore /etc/libvirt/qemu/VZ02-zentyal.xml from the saved copy
7) restart virt-manager -- Now virt-manager starts, the VM have an IDE bus and an IDE CD (strangely the /etc/libvirt/qemu/VZ02-zentyal.xml file is untouched and there is no cdrom stanza)