Wow GSteer, that is some wild manifestation.
Out of curiosity, do any of those ePubs have apostrophe's in the filename? That seems to be a pretty common reason for this message. Does removing the apostrophe help in any of the cases? I've been able to make the message go away via removing apostrophe's, but granted I only tried to access them via the I'm Reading list when they are new, not from the bookshelf.
I don't really want to mess around with tracking this down, but I would be very curious to learn about your tinkering
