GPG functions failing intermitently with specific key on specific machine

[green at mm.st]

Hi,

I recently added a post to the gnupg-users mailing list
(http://marc.info/?t=140684231100001&r=1&w=2) concerning an issue I'm
having with gnupg on my Arch Linux machine.  After a few useful
suggestions, a couple of the users there have suggested that I now
create a new post on gnupg-devel, in order to see if someone with
expertise with the gnupg code can help.

In summary:

- I have gpg set up on two machines, one running Arch Linux (gnupg
2.0.26, libgcrypt 1.6.1) the other Windows 7 x64 (gpg4win 2.2.1).
- I originally had only one private key.
- gpg2 functions using that key on the Linux machine fail intermittently
(e.g. with a "Bad signature" error, when clearsigning).
- gpg2 functions using the same key on the Windows PC succeed
consistently.
- I have since created a new keypair.
- I can encrypt consistently and successfully with the new private key
on *both* machines.
- I have deleted the problematic private key on the Linux machine,
exported it from the Windows machine and re-imported it on the Linux
machine, but the intermittent errors still occur with that key.

I would be very grateful if anyone could help?  Please also let me know
if there is any additional information I could provide which might help
diagnose the problem.

Many thanks,

Wolf.