Well, I have just discovered today that FRELLING AMAZON has put DRM on FREE BOOKS downloaded from the Kindle Store. What this means is that even though the books are free, I can't read them in the Calibre ereader. So, I deleted them all and redownloaded them from Project Gutenberg whilst watching the game. Lessons learned. Sadly, purchased content from Amazon for the Kindle will still have this problem. VV Annoying.