Corrupt book downloads
My wife and I share an AppleID for our purchases. These include iOS apps, OS X apps, music, films, tv programmes and books.
We have separate iCloud accounts for all other cloud data.
My wife has a mid 2011 iMac with 10.10.4, an iPhone 5S with iOS8.4 and an iPad 2 with iOS7.
I have have late 2013 rMBP with 10.10.4 and an iPhone 6+ with iOS8.4
Now if my wife purchases or downloads a book on any of her computer or devices, they are corrupt and cannot be opened.
If I download the same publications to my equipment, they are OK and can be opened and read.
If I delete them off her OS X iBooks app and downloading them again, they are still corrupt.
If I delete them off her iOS iBooks app on either her iPad or iPhone, again when they are downloaded, they are corrupt.
I can delete them as much as I like and download them to my computer and phone, all books are OK.
Does anyone have any idea why one set of equipment are corrupt and the other all OK?