Copying Ebooks - Message "Failed To Load Because The Necessary Resource Is Missing"

We put much of our iTunes music on both my and my wife's desktop and we both sync them to our respective IDevices (ipods, iPhones, iPads)

This morning I tried copying an iBook from my wife's library to mine. It seemed to show up in my library and when I synced my iPad, it appeared on my shelf but when I clicked on it to read it, I get the message "Failed to load because the necessary resource is missing"