I used to have a kindle and it would periodically lock up and I'd have to do a hard reset and then re-download all my books. It was extremely frustrating. I finally got tired of it and ditched ti for a Kobo Clara. Whats nice about the Kobo is that it doesn't have all the janky DRM bullshit, and it just works. You can load up books or pdfs from any source. So much happier now!