It's probably something else especially if you have the latest nVidia driver. Although it could that latest driver version.
I think you have to unplug the burner. See if it works then. If not, then you need to take everything you can out of the systray and shut down your browsers and see if the screensaver will come on and/or the monitor turns off. Set the monitor to turn off at a shorter time while you are troubleshooting. It could even be something like your mouse...something is keeping the monitor on. If you eliminate as much as you can and it does turn off then add back one at a time until you find the culprit.
Try a different screen saver...ribbons should be ok, but then Photo Gallery, which is from Microsoft, should be ok also as a screen saver on my new Win 8 computer. However, if I use it for the screen saver my monitor never turns off. If I use "Photos" (different from Photo Gallery). or "ribbons". or even no screen saver. the monitor turns off when it is supposed to, but not if I use Photo Gallery which I really like and want to use. It could be almost anything causing your problem. It never occurred to me, years ago, with a new computer and nVidia card that the latest driver update was preventing my monitor from turning off. Only when I finally saw posts at nVidia forums about it did I realize that was the culprit.
When governments fear people, there is liberty. When the people fear the government, there is tyranny. Thomas Jefferson