Strange behavior with image sizes (SOLVED)

I am experiencing a strange behavior with image sizes in page posts. Some images I insert into a page in full size (900 pix aprox) appear ok in the editor but once live on the page appear much much smaller. I inserted them in full size but they appear as some sort of thumbnails. The weird thing is that only some images behave that why.

I am not sure if is a GP bug or a Wordpress one.

I would really appreciate some help/insight into this because it drives me crazy and can't continue adding images to pages with images. Thank you.
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Solved the problem, it was an issue with a div tag.