Grainy pictures - Nikon D100 Digital Camera

have you tried resetting the pixel setting for the screen
that is what causes grainy screens

I'm assuming here that this tv is being used for analogue reception because on digital you either get a perfect picture or when the signal is weak enough, nothing at all (common when trying to use rabbits ears or in poor reception areas). Assuming analogue then, when the signal is weak (grainy or snowy picture) the colour (called chroma) is automatically turned off because grainy colour is unwatchable. This is normal. Solution, a better aerial to provide a stronger signal.

You need to check your ISO setting and the picture quality you have your camera set to. It should be at the maximum megapixels and fine quality and the ISO should be below 800 or even 400.

You have a couple of options.
1. Turn down the sharpness on your TV. Too much is overkill, anyway.
2. Whilst watching any movie, hit the triangle button for the movie settings & options. Turn up the noise reduction to +3, also the "mosquito" noise to +3.
These should give you a less grainy picture. Enjoy!

Problem is your CCD has failed. Expensive repair.

The grainy effect has to do do with the ISO setting, try adjusting that. A higher ISO is generally better for darker conditions. I have noticed that this camera frequently takes grainy images.

If you can adjust the ISO sensitivity to a lower number then the graininess will be reduced.

However, by reducing the ISO, you will need a slower shutter speed and a larger aperture. A tripod, table or other support may be necessary.

The "noise reduction" setting on the camera can also be adjusted a step up.

Taking pictures at full resolution and fine compression will also help.
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Overall, at least try lowering the ISO, and using the flash brighter.

grainy pictures are possibly casued by a very high ISO (sensativity) setting, you should be on 100 or lower for best normal shots. Higher settings are for low light and custom shooting in strange lighting or aperature/shutter speeds. Try full auto setting.

You have your ISO setting far too high - set 100 or 200 and get a magic improvement immediately !

it could be a problem with CCD, and that can just be replaced in a service centre.