Windows 7 - aero transparency problem

hi! i really need your help. i have new computer with asus p8z68 deluxe motherboard and asus nvidia geforce 550 ti graphic card. immideatly after installing nvidia drivers on clean windows 7 installation, aero transparency works, and also windows experience index, but after couples of restarts and installing things - aero transparency stop working. if i reinstall nvidia drivers - transparency is back, until next restart, and windows experience index also stop working. troubleshooting says that problem with display drivers - i should install wddm drivers, but the problem exists even if i install nvidia drivers via windows update, and not from nvidia/asus website

Are you sure you're on aero? You can check this by right clicking on your desktop and clicking personalize. Now press the 'windows 7 aero theme'. If it is not transparent, 'click on windows colour' at the bottom, and change the transparancy setting. Many people get stressed out, because theyre on windows basic, not windows aero.

-Rowan