Error message: "E_ADEPT_CORE_KEY_SCRAMBLE"

I tried to open with Adobe Deigital Editions an EPUB-file, which i downloaded from Google Play books. Now I get an Error message: "E_ADEPT_CORE_KEY_SCRAMBLE". Where is the problem. Earöier is ha workes perfectly. Also Files I have downloaded earlier are working okay.

Any help appreciated.

jorma