Transferring e-pubs aborted. ADE stops responding

1) When I transfer my downloaded E-pub to the ADE Library I get the message: "Impossible to transfer etc. the document is already present in the library", but there is no e-book present; 2) When I transfer an DRM-protected e-pub, the e-book can be seen in the library, but then ADE stops responding and I must reboot. I have unistalled and reinstalled ADE several times, but without results.