I have had ongoing problems loading books to my Kindle. I have done everything suggested to clear the problem which, on reflection seemed to start when my son shared books with me.
Recently I downloaded 3 Terry Goodkind- The Sword of Truth no problems that I could see on a quick glance through so I downloaded the another two prior to going away. Only to find I was back to the same old problem of having spurious letters and lines superimposed. . Kindle and the bin seem to now have an increasing affinity.