Need help decrypting (gnuPG 1.2 - winnt4)

[Michael_Gold@glic.com]

Hello,

I am trying to decrypt a file that was encrypted by another party using my
public key.  They encrypted using PGP5 and swear they used a CAST5
algorithm.  However, whenever I decrypt the file I get the following error
message:

D:\OpenPGP>gpg pgptest.asc
gpg: cipher algorithm 1 (IDEA) is unknown or disabled
gpg: the IDEA cipher plugin is not present
gpg: please see http://www.gnupg.org/why-not-idea.html for more information
gpg: encrypted with 1024-bit ELG-E key, ID 9A38872F, created 2002-10-07
      "Guardian (UCLA - NIPR Signing And Encrypting Key - DSA and ElGamal)
<ucla@glic.com>"
gpg: public key decryption failed: unknown cipher algorithm
gpg: decryption failed: secret key not available

Is IDEA definately the problem?  Or is this error message not indicative of
the real problem?  Note all other gpg operations seem to work fine and when
I encrypt and decrypt the file myself its ok.

Also, just to prove whether or not IDEA is the problem, I'd like to try the
idea.dll plugin.  I've downloaded the dll and did a regsvr32 in the same
dir as my gpg binary, but it makes no difference.  Is there a way I have to
tell gpg to use it?  I didn't see anything about it in the manual.

Any help or suggestions are greatly appreciated.

Thanks,
Mike