jpgs having more detailed parts inside explorer thumbnail view ,why ?

[auto78900]

I have some jpg pictures, on my c drive. When I view them in explorer as a thumbnail view , I see that everything is visible, but when I view the jpg picture with Windows Picture & fax viewer(or any other picture viewer), I see that some parts in the middle of the photos either have a black box , or a blurry circle in the middle . What is this and is there a JPG viewer that can display the whole picture the same way as the thumbnail view ,but this time in full size including without the black box in the middle or blurry circle in the middle of the photo ?

[Anbesol]

The thumbnail is pretty small relatively to a full screen view in windows picture viewer. Can you post a sample image for us?