Oh no - first thing I tried. There are no restore points at all - all those have been deleted as well. It is almost as though some form of virus got in on top of Win update.
Thanks for your comment Saab. I have had problems before by updating hardware drivers - these were all original.
If my original Win 7 disk will not repair the system then it is a case of re-formatting and starting again I suppose. At least they can't do this to XP any more as they are no longer updating it!
P.P.