Originally Posted by PeterT
This sounds likes a corrupted database on the Kobo; only way to fix that is a factory reset and then reload books.
However before trying that have you verified that the time and date are correct on the Kobo?
Although I tend to agree with your diagnosis, I would suggest before going for a factory reset, trying the log out and log back in approach. That way, you don't lose everything on the reader. If it doesn't work, you can still do a factory reset.