Fedora xen - Sep 2007 - Problems installing DomU on a new system using virt-manager

Fedora 7 - fully updated with yum.

I''ve just built a new x86_64 system Intel Duo Core 2 E6420 on an Intel
DG965WH mb.

There appears to be a major bug (amongst many others) in virt-manager
which only appears when installing the very first DomU. 

If I try to install the first DomU connecting to a virtual network the
install fails every time right after I configure the network interface
when retrieving stage2.img. It just hangs restarting the DomU results in
a boot failure message.

If I install the first DomU using a shared network the install is
successful. Now for the fun part. If then I delete the DomU supposedly
returning to a clean slate I can now install DomU''s using a virtual
network. 

It appears that installing the first DomU using a shared network changes
something that causes virtual network DomU''s to install successfully
even if the first "shared network" is simply installed and then
immediately deleted.

Does anyone have any suggestions as to what might be happening?

Does virt-manager use any install scripts, if so can they be customized?

Regards John