Patria,
I'm not sure that we know what's causing this at this point. Once ADE 1.5 has been installed it should stay installed, and books that you've already downloaded and activated should work fine.
Please open a web Technical Support case at http://www.adobe.com/support/contact and we'll try to figure it out. Be prepared to provide your OS and Flash Player version to get started.
Regards,
Bentley Wolfe
Senior Support Engineer, Flash/Flash Player
Adobe