libvirt users - Oct 2013 - Upgraded to F18: now machines won't start

We've gone back to using an older machine that used to run libvirt just 
fine. Updated to F18, libvirt-1.1.0-1.fc18.x86_64. VirtualBox works ok.

Now I can't start any image.

For one machine i get:

..............
File "/usr/lib64/python2.7/site-packages/libvirt.py", line 698, in
create
     if ret == -1: raise libvirtError ('virDomainCreate() failed',
dom=self)
libvirtError: internal error Cannot find suitable CPU model for given data

that's whether I use what we used to use "Phenom" or the selection
from
allowing virt-manager to choose "Opteron G3".

For another machine we get:

libvirtError: internal error Process exited while reading console log 
output: char device redirected to /dev/pts/37 (label charserial0)
failed to initialize KVM: Device or resource busy

Doing some debugging, I found:

1. On boot the kvm_amd and kvm kernel modules won't/don't load. Nothing 
in dmesg. Modprobe does load them.

lsmod | grep kvm
kvm_amd                59982  0
kvm                   429349  1 kvm_amd

I still can't make anything work with the modules loaded.

2. When I start libvirtd, I get:

Oct 30 14:56:29 sixcore systemd[1]: Starting Virtualization daemon...
Oct 30 14:56:29 sixcore systemd[1]: Started Virtualization daemon.
............
Oct 30 14:56:31 sixcore kernel: [  837.705913] kvm: enabling 
virtualization on CPU5 failed
Oct 30 14:56:31 sixcore kernel: [  837.705920] kvm: enabling 
virtualization on CPU4 failed
Oct 30 14:56:31 sixcore kernel: [  837.705928] kvm: enabling 
virtualization on CPU1 failed
Oct 30 14:56:31 sixcore kernel: [  837.705934] kvm: enabling 
virtualization on CPU2 failed
Oct 30 14:56:31 sixcore kernel: [  837.705946] kvm: enabling 
virtualization on CPU3 failed
Oct 30 14:56:31 sixcore kernel: [  837.745267] kvm: enabling 
virtualization on CPU0 failed

I looked at the wiki on how to debug, and I seem to pass all the tests.

virsh capabilities | grep kvm
       <domain type='kvm'>
         <emulator>/usr/bin/qemu-kvm</emulator>
       <domain type='kvm'>
         <emulator>/usr/bin/qemu-kvm</emulator>

virsh dumpxml 2008R2 | grep kvm
<domain type='kvm'>
     <emulator>/usr/bin/qemu-kvm</emulator>

Am I right that some of the entries in the xml file have now changed? Is 
there a guide to updating them from the prior entries?

And, if I try to create a new machine, virt-install just hangs:

virt-install --prompt
What is the name of your virtual machine?
New-2008R2
How much RAM should be allocated (in megabytes)?
1200
What would you like to use as the disk (file path)?
/opt/storage/virt/windows/images/2008R2.img

ls -l /opt/storage/virt/windows/images/2008R2.img
-rw-------. 1 root root 23571726336 Dec  8  2012 
/opt/storage/virt/windows/images/2008R2.img

I changed the permissions to 666. still hung.

Any help appreciated.

Sean