There can be a number of things that could be causing this:
Windows Experience Index
Aero is compatible, but you just haven't realised Try this:
Windows + Pause Brake (On your keyboard) then click 'Advanced system settings'. Under Performance, click 'Settings...' then click 'Adjust for best performance'. Hit 'Apply', then after that click 'Adjust for best appearance then click 'OK'.
If that doesn't work, Windows + Pause Brake again, then click 'Windows Experience Index'. If it asks you to run the test, then run it and see if it helps.
If both options fail, go on to your laptop manufacturers website (If you're using a laptop/notebook) and search for the drivers
there, otherwise go to nvidia.com
and download the latest drivers. (Don't ever go to an unofficial driver website, it's just asking for trouble)
If still nothing, and you haven't backed up your driver, try and see if you can download an earlier driver.