I am sure I sent an email reply saying I reinstalled the server, then switched to the KVM option which there were no issues what so ever for me, once the bridge was setup and the correct settings applied it was very much out of the box situation and was working in less than 2 hours.
However for Xen I think you need to look at your options as they do not seem to be as so simple as they did for KVM as there was a lot of issues with mods being installed and correct software like lx and xm being mixed up.
I have a few nodes running the software under openvz until I tried the Xen option I have never had call to ask for help and I feel with the KVM I will also have no need to request help.
As above sort out the issues with Xen I tried many of your supported OS they all seemed to have issues of one kind or another so that is the bit with the product you need to fix.