What graphics set up do you have? Is it a) just onboard graphics chipset b)just graphics card (no graphics chipset) c) graphics card + graphics chipset (with monitor presumably attached to graphics card port). As from diagnostics you provide you can not do a 'restore' you are looking at doing a 'repair' or failing that a full reinstallation' of windows unless you have setup c) whereupon you can take out the graphics card and run off the graphics chipset so you can remove CCC 8.6 (even this may not work). As for why it is happening - probably ATI **** catalyst drivers, unlikely but possible coincidence is your machine has developed another fault. If you give specs of your machine (at least the motherboard and graphics card) then maybe other people with the same kit can give you a better headsup.