Hello Mark Lloyd,
Please let us know the model of your NUC for further investigation on this matter.
I have been testing with Server 2008 and 2012 which is probably not strictly supported on that motherboard but the same still happens on Windows 8 also.
It doesn't seem to be O/S related IMHO.
I have also just updated my unit to latest release BIOS (Version 0040) which I was emailed about a few days ago.
BIOS upgrade went fine and O/S started fine. Then performed a restart as I wanted to go into BIOS to confirm versions etc etc and the restart failed. The unit is just sitting there with solid blue power light and no video.
As I now have some apps running on the NUC unit I thought I might just test them via remote and they are up and running so the system actually did start fine! Great news.
This actually appears to be more of a video issue now where the monitor is not sensing any video output or some thing like that.