Cannot use GnuPG with Icedove in my desktop but can in my laptop

[Ken Heard <kenslists@teksavvy.com>]

I have a laptop and a desktop.  Both have squeeze, the latest versions
of icedove (10.0.12-1) and enigmail (2:1.4.1-2) from squeeze-backports
 and gnupg (1.4.10-4+squeeze1) from squeeze installed.

On the laptop I can digitally sign my e-mails, but I cannot on the
desktop.  The laptop can find the gnupg key list (~/.pubring.gpg?),
but the desktop cannot.  (In both computers I can see the key list,
including my key,  by clicking on the lock in the panel.)

I tried using the wizard available from the "OpenPGP" button on the
Icedove top level tool bar.  In the laptop it finds my personal key,
but not in the Desktop.  In the wizard on the desktop I entered the
gnupg keylist file (~/.pubring.gpg) on the page where the wizard asks
for it, but the list did not appear.

After trying but failing to send a signed message from the desktop the
following message is returned:

Send operation aborted.

Error - encryption command failed

gpg command line and output:
/usr/bin/gpg
gpg: skipped "0xE9099937": secret key not available
gpg: [stdin]: clearsign failed: secret key not available

So icedove knows my correct keypass but cannot find the key.  The
desktop would presumably know my keypass because I started to use
icecove & enigmail on the laptop and later transferred my icedove mail
and config files from the laptop to the desktop.

To be able to send e-mails from the desktop I had to disable the
option to sign them.

Can anybody suggest how I can rectify this strange behaviour in the
desktop?

Regards, Ken Heard