In late January, NVIDIA introduced in tis drivers the Supersampling option. It essentially renders the game in up to quadruple resolution, and scales it back down to your actual resolution. This is a specific anti-aliasing method, rarely implemented in games (Witcher 2 was an exception, and called it "Ubersampling").
It is enabled by default on GTX 980 cards, and optional on others.
It has been known to cause launch issues with older games, as it forces them to use an unsupported resolution.
To disable this option, right-click your desktop and select "NVIDIA Control Panel". Go to "3D Settings" and find the "DSR - Factors" option. Un-select all possible settings and confirm. This should change the setting to "Off". Apply the changes and check if this resolved the issue.