I got my answer. The server won't even boot off a virtual DVD (used as you would boot from a disk to help with a booting problem with your own OS) which shows it was nothing I done, honest! (Blame Zab)
But anyway, I've just been told "This machine seems to be experiencing some sort of Xen-related issue. I've triggered a move to another machine for you now and I will follow up to make sure this works." So it was all about the Xen, I thought so, I was just thinking to myself "I bet its that damn Xen again". So, yea, so obvious... Anyhoo, should be alive and well soon I hope
