invalid packet (ctb=2d)

[Sjokotof]

Situation:
- production system Win32 running PGP 6.5.8, daily decrypting a series of 
incoming files.
- trial setup Win 32 running GnuPG 1.2.5, decrypting the same series of 
files.
- Trial ran OK for months, with the exception of a few days ago, when one 
of the files choked GnuPG, but ran fine through GPG.

Below the output.
What can be done to get this decrypted by GnuPG?

========
gpg --list-packets gives:

gpg: armor header: Version: PGP 6.5.8
:marker packet:
 50 47 50
:pubkey enc packet: version 3, algo 16, keyid (ID1)
        data: [2047 bits]
        data: [2048 bits]
gpg: public key is (SECONDARYKEY)
gpg: using secondary key (SECONDARYKEY) instead of primary key
(PRIMARYKEY)
:encrypted data packet:
        length: unknown
gpg: using secondary key (SECONDARYKEY) instead of primary key
(PRIMARYKEY)
gpg: encrypted with 2048-bit ELG-E key, ID (SECONDARYKEY), created
2001-04-09
      "(RECIP)"
gpg: CAST5 encrypted data
:compressed packet: algo=1
:onepass_sig packet: keyid (ID2)
        version 3, sigclass 00, digest 2, pubkey 17, last=1 :literal data 
packet:
        mode b (62), created 0, name="rh370r01.rpt",
        raw data: 0 bytes
gpg: [don't know]: invalid packet (ctb=2d)
gpg: [don't know]: invalid packet (ctb=2d)
gpg: WARNING: message was not integrity protected
gpg: [don't know]: invalid packet (ctb=2d)

================================

gpg 1.2.5 gives:

gpg: armor header: Version: PGP 6.5.8
gpg: public key is (SECONDARYKEY)
gpg: using secondary key (SECONDARYKEY) instead of primary key
(PRIMARYKEY)
gpg: using secondary key (SECONDARYKEY) instead of primary key
(PRIMARYKEY)
gpg: encrypted with 2048-bit ELG-E key, ID (SECONDARYKEY), created
2001-04-09
      "(RECIP)"
gpg: CAST5 encrypted data
gpg: original file name='rh370r01.rpt'
gpg: Signature made 10/01/04 08:50:29  using DSA key ID (DSAKEYID)
gpg: Good signature from "Merrill Lynch CLEAR system DH <clear at ml.com>"
gpg: WARNING: This key is not certified with a trusted signature!
gpg:          There is no indication that the signature belongs to the
owner.
Primary key fingerprint: (FINGERPRINT)
gpg: binary signature, digest algorithm SHA1
gpg: WARNING: message was not integrity protected
gpg: [don't know]: invalid packet (ctb=2d) 

================================ pgp gives:

Pretty Good Privacy(tm) Version 6.5.8
(c) 1999 Network Associates Inc.
Uses the RSAREF(tm) Toolkit, which is copyright RSA Data Security, Inc.
Export of this software may be restricted by the U.S. government.


event 1: initial
event 13: BeginLex
event 8: Analyze
File is encrypted.  event 9: Recipients
Secret key is required to read it.

Key for user ID: (RECIP)
1024-bit DSS key, Key ID (KEY), created 2001/04/09 Key can sign.
event 6: Passphrase
event 23: Decryption
symmetric cipher used: CAST5
event 11: Output options
typecode: 0062
suggested name: rh370r01.rpt
tempfile: created 'Copy of ba.$00'
event 12: Signature
Good signature from user "(SENDER)".
Signature made 2004/10/01 06:50 GMT
event 14: EndLex
event 2: final
savetemp: renaming 'Copy of ba.$00' to 'Copy of bad 
rh370r01.rpt.asc.04.10.01_02.50.txt'

0 memory frags found
exitPGP: exitcode = 0
=============