The problem is solved!
I went to ebook by way of Windows Explorer and found a file with the same name as the one that originally caused the problem. I couldn't see it within the reader or the library. When I tried to open it with Windows, I couldn't because it was corrupted. So I deleted it and the problem was solved. I think that each time I connected the reader to the computer the library was trying to read the corrupted file and after 5 minutes just gave up.
Thanks to all who read the original post and were thinking of a solution.