Comment 6 for bug 347765

One more occurrence gave the following warning
******************
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 hardy-updates Release:
The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <email address hidden>

W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/hardy-updates/Release

W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/hardy-security/main/binary-i386/Packages.bz2 Hash Sum mismatch

W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/hardy-security/universe/binary-i386/Packages.bz2 Hash Sum mismatch

W: Some index files failed to download, they have been ignored, or old ones used instead.