gpg: checking created signature failed: Bad signature

[Wolf]

Hello everyone.  I'm new to mailing lists so apologies in advance if I commit
any faux pas.

I'm trying to sign a public PGP key but am encountering a 'Bad signature' error:

    gpg --edit-key someone at somedomain.com
    ...
    gpg> sign
    ...
    You need a passphrase to unlock the secret key for
    user: "My User <myuser at mydomain.com>"
    2048-bit RSA key, ID 12345678, created 2012-01-01

I enter my passphrase then get:

    gpg: checking created signature failed: Bad signature
    gpg: signing failed: Bad signature
    gpg: signing failed: Bad signature

I'm also sporadically getting the same result when clearsigning messages in
mutt.

I've done some searching online but can only find old, unrelated posts or ones
relating to smart cards, which I'm not using.

The wording of the error seems to suggest that gpg is attempting to verify the
signature it just created but is failing?

I'm running gnupg 2.0.25-1 on an Arch Linux box via a PuTTY SSH connection.

Any help gratefully received!

-- 

/Wolf

[GnuPG Key: A8E50255]