A thought just occurred to me so thought I'd post it fwiw - most of us have second-hand copies of NAP.
I can't be sure, but I would suspect if it made someone a millionaire and/or solved all their problems, they may not have parted with it, so MAYBE (this is only theoretical) the people who owned it before had, or did, something that was out of line with the system.
For example maybe they believed that the best magick is the kind where you have to be all evil, all the time, beccause they were really just nasty little shits who wanted an excuse, and offended badly against the spiritual entity of the book - or maybe they had some religious or other belief, picked the book up out of a desire to prove it wrong, and caused the resident forces to shrivel away... etc.
If it's true that each grimoire carries a link directly then you're not just owning a thing, you're also buying the shared spiritual content - maybe these people got the copies "disconnected" through some action of their own?
It would be a bit like buying a second-hand iPhone on trust from e-Bay, only the previous owner ran up huge bills and it's been disconnected from the network - or, worse, it belonged to a drug dealer and the FBI are still tapping it, they've now put you under surveillance for using his phone, and his gang warfare enemies have tracked you via the network. Silly example maybe but that's kind of the image I had when it first occurred to me.
Anyway just a thought as I said, I don't have any proof or anything - but for anyone reporting a problem, and it's happened enough now that I think it's worth addressing, maybe you could do a simple blessing or cleansing (which I guess many people really new may not have done, including maybe people who haven't joined the forum but read threads sometimes) then summon back with a quick prayer or whatever the actual spiritual force of the book, as its author intended.
If I recall correctly someone said that GG-C did some kind of work with the printer to ensure that the book carried that connection, although I can't recall which thread it was in.
IOx