I have read more complicated instructions on this in other areas. I believe there is an easier way to de-aunthorize/ re-authorize your PDN on ADE. Open ADE on your pc, turn on your novel and connect it to pc. Then press Ctrl,Shift, E. You should get a box asking of you want to deauthorize, select yes. Repeat the process and you should get a box saying that a new device has been detected and you can authorize it. This should fix any problems with putting DRM books on your PDN. I have the 8-6 update on mine. Please post your results!