Windows 10, right? It's quite likely something did update unknowingly and has corrupted things. You can force windows to stop automatically updating if you are having an issue with this.
http://lifehacker.com/enable-metered-co ... 1723316525 Unfortunately, this disables all updates to Windows, so it isn't a long-term solution. (This is the one reason I haven't upgraded Win 8 yet as from what I've used of 10, it is better and faster than 8.) Once you do this, you can go get the official drivers from Nvidia*. If the official drivers are still doing it, get the previous posted ones.
*probably wouldn't hurt to file a bug report with Nvidia about this.
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