Hey! I just tried transferring some files from my iMac to my Macbook pro and when i send them through Air drop it says that the transferal was canceled immediately after i tried to send something, why is that? Then i tried to send something from my macbook pro to my iMac and i got an error message that said" The apple id certificate for "xxx iMac" is invalid. the transfer has been canceled. How do i fix this?!?!? help!!!