What's wrong with my Nikon D7000?

What's wrong with my Nikon D7000 camera.whenever i take image, there's always a blue spot on the top left of the image. Is this because of the dust on sensor or in lens? I'm posting the link fo some images. Please tell me the solution.

Yes that is dust - most likely on the sensor. But you can confirm it by using a different lens, or try and clean your lens first.

The D7000 has a dust shaker built into it. By default, it should operate every time you turn the camera off. The dust shaker literally shakes the sensor to knock dust off it.

So first, see if you turned that off. Also, you can run the "shaker" at any time you want, so try it a few times.

If that doesn't work, you will have to clean the sensor, or have it done. If you are adept at things complicated, you can buy a special cleaning kit for your sensor - such as those made by "Photographic Solutions". For Nikon, you want the Type 2 cleaning kit.

http://www.photosol.com/store/pc/home.asp

But you could risk damaging your sensor by doing it yourself, so consider having it cleaned by a trained camera technician if you don't feel comfortable in doing it yourself

Here is a webpage showing how I cleaned the sensor on my D70 a couple of years ago.

http://www.althephoto.com/tips/clean.php