problems with Calibre and PDF: Error: Couldn't find the 'Adobe.APS' security handler

[any ANONYMOUS forum user]

What should I do?

C:\>calibredb add CS5.pdf
Error: Couldn't find the 'Adobe.APS' security handler
Traceback (most recent call last):
File "site-packages\calibre\customize\ui.py", line 295, in get_file_type_metad
ata
File "site-packages\calibre\customize\builtins.py", line 346, in get_metadata
File "site-packages\calibre\ebooks\metadata\pdf.py", line 25, in get_metadata
RuntimeError: S# is password protected.
IneptPDF: Calibre configuration directory = C:\...\calibre
IneptPDF: Created keyfile from ADE install.
Ready to start decrypting.
Error serializing pdf. Probably wrong key.
IneptPDF: Encryption key invalid... trying others.
Running file type plugin Inept PDF DeDRM failed with traceback:
Traceback (most recent call last):
File "site-packages\calibre\customize\ui.py", line 148, in _run_filetype_plugi
ns
File "calibre_plugins.dummy3.__init__", line 2223, in run
ADEPTError: IneptPDF - Ultimately failed to decrypt
Backing up metadata
Notifying calibre of the change

C:\>