Tweakforce modified drivers can introduce blur.

[Nicholas Steel]

http://www.tweakforce.com/

Using unofficial drivers from here can introduce a blurred effect to the ZC Player. This is just a note to let people know in case they encounter this "blurred" effect too.

[BFeely]

Are you using a digital connection for your monitor and running at 320x240? If so, your NVIDIA drivers are likely set to "NVIDIA Scaling" in the control panel.
If you hook your monitor up by a VGA cable, it will use the VGA Mode-X resolution, which doubles the pixel size. However, NVIDIA scaling does not double the pixels in low resolutions, resulting in a blurred effect. I had this happen with official drivers.