Just a note, I updated to the NVidia 191.xx series driver, from the 190.xx version, on my notebook and my desktop PC. Both crashed whenever I used the scrollbar to scroll down the effects or transitions area. I went back to the 190 series and it's fine again.
Just a note the latest 191.xx series drivers from NVidia caused PE7 to become unstable on both my PCs, both running 64 bit Vista.
Check out this thread, there have been quite a number of posts on various Forums concerning nVidia issues with the latest drivers:
The second post in this thread may be revelant...