Windows System Restore *WILL* restore NV1 books! (I know for a fact – it saved my bacon recentyly.)
The file extension ‘NV’ is one that Windows considers to be a ‘system file’ and therefore NV1 books (DATAD.NV) is caught up in system rewtore operations. (Ever notice the long pause when you open a large set of NV1 books? That’s system restore making a backup.)
So, there is no mystery here – wehen you did a system restore to remove that program it also restored old copies of your NV1 books.
The only way I know to avoid all this is to save your books on a drive other than C:.