Refused to boot : boots so far and then reboots and goes into a constant boot/reboot loop.
Run in safe mode line by line. The last load is ClassPnp.sys then it reboots.
Boot from disc into repair and get the 'unable to repair'.
Try to restore and get 'unable to restore', despite selecting one of several different restore points.
Cannot get into safe mode to run anything.
Off to try some of Greg's recommendations now.
thank you, Gordie