Currently Being ModeratedJun 21, 2013 5:05 AM (in response to KevinWAT)
How are you getting the .ibooks file? Is it through iBookstore via iTunes, or supplied in an email/FTP/Dropbox, etc?
I have had email attachments go strange from Mac>PC. If they zip it at their end before sending, and you unzip it, it should unzip as .ibooks OK.