Reloading repositories with synaptics generates W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://archive.ubuntu.com precise Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <email address hidden>

Reloading repositories with synaptic generates "W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://archive.ubuntu.com precise Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <email address hidden>"

The problem then persists in Update Manager, Synaptic and apt-get update.

Problem is fixed using:
# apt-get clean
# cd /var/lib/apt
# mv lists lists.old
# mkdir -p lists/partial
# apt-get clean
# apt-get update

At this point using Update manager or apt-get update generates no errors, the error returns when reloading with Synaptic.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: synaptic 0.75.5~exp6
ProcVersionSignature: Ubuntu 3.2.0-17.27-generic-pae 3.2.6
Uname: Linux 3.2.0-17-generic-pae i686
ApportVersion: 1.93-0ubuntu2
Architecture: i386
Date: Mon Feb 27 13:22:07 2012
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Alpha i386 (20120201.1)
ProcEnviron:
 LANGUAGE=en_US:en
 TERM=xterm
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: synaptic
UpgradeStatus: No upgrade log present (probably fresh install)