failed decryption

[Adam Gold]

I'm attempting to decrypt a symmetrically encrypted tarball appx 25GB in
size.  It goes as follows:

gpg [file].tar.bz2.gpg
gpg: AES256 encrypted data
gpg: encrypted with 1 passphrase
gpg: packet(7) with unknown version 41
gpg: WARNING: encrypted message has been manipulated!
gpg: packet(5) with unknown version 241

To my totally untrained eye this seems pretty bad.  I also tried the
same decryption using the commercial PGP suite and had a similar
(although not identical error).

Is there anything I can do, further debugging?