پس از باز کردن update manager و زدن دکمه check و دانلود کردن ناقص چند بسته با پیغام زیر روبرو میشم
W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used.GPG error: http://us.archive.ubuntu.com jaunty-updates Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <ftpmaster@ubuntu.com>
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/jaunty-updates/Release
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/jaunty-security/main/source/Sources.bz2 Hash Sum mismatch
W: Some index files failed to download, they have been ignored, or old ones used instead.
چه کار باید کنم ؟