I have had this problem with Vista on and off since I got it about 18 months ago. I have found loads of references to it when googled and no permanent cures.
Unlike XP I can find no means of re-installing system restore.
My solution - turn it off and use Acronis True Image v.11. At least you know it's going to work when nasties happen, unlike system restore which, as far as I am concerned is thoroughly unreliable.