ADE cannot open and cannot deauthorize

I cannot open my books in Adobe Digital Editions. I tried to follow the steps: 'Press Cmd-Shift-D to deauthorize Adobe Digital Editions.'

But when I do this it just says: ' Unable to Erase Authorization. Please try after some time.'

I have now tried a lot of times and it still does not work. I have tried to uninstall the program and install again. It does not change anything.

Please help.

Maria