I have tried to install this important security update both automatically when closing down my windows 7 computer and also manually several times but it will not install. I cannot use windows restore to go back before this update appeared but it won't go back far enough and I have also tried the microsoft windows update 'fixit' option which does not work. The error code 80070683 appears but the windows help options on this are useless. Has anyone got any solution to this please? It keeps trying unsuccessfully to install this every time I shutdown my pc!!