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It is a problem with the printhead because the printhead is the part of the printer which puts ink on the paper.
As of first step, let's try manually cleaning the printhead.
Take a paper towel and fold it into 4 turns and make it little thick. Then add little rubbing alcohol to it and then place it in the path of the printhead carriage. Then move the printhead carriage over it a few times.
Please follow this link to see a video : http://www.youtube.com/watch?v=yrAqXjX10xs
Tell me if it makes any difference to your problem.