Attempting about the dozenth Windows install of the day.
If this one fails as well (on recent experience this seems likely!) I'll keeping on going tomorrow before I give in, send the box off to our support bods, and order a new one.
That way I'll get the OS installed eventually, but get a working box in a couple of days so I can do what I need to do with it. The older one will probably be returned eventually, but I'm not expecting it to be particularly fast!