Comment 72 for bug 24234

I'm running Ubuntu 10.04.3 LTS and I just got the error described today. I received this as output to sudo apt-get update today:
_US
Ign http://download.skype.com stable Release
Ign http://packages.medibuntu.org/ lucid/free Translation-en_US
Hit http://download.skype.com stable/non-free Packages
Ign http://packages.medibuntu.org/ lucid/non-free Translation-en_US
Hit http://packages.medibuntu.org lucid Release
Hit http://packages.medibuntu.org lucid/free Packages
Hit http://packages.medibuntu.org lucid/non-free Packages
Hit http://packages.medibuntu.org lucid/free Sources
Hit http://packages.medibuntu.org lucid/non-free Sources
Hit http://download.virtualbox.org lucid Release.gpg
Ign http://download.virtualbox.org/virtualbox/debian/ lucid/contrib Translation-en_US
Ign http://download.virtualbox.org/virtualbox/debian/ lucid/non-free Translation-en_US
Hit http://download.virtualbox.org lucid Release
Hit http://download.virtualbox.org lucid/contrib Packages
Hit http://download.virtualbox.org lucid/non-free Packages
Fetched 5,267B in 10s (489B/s)
Reading package lists... Done
W: GPG error: http://archive.canonical.com lucid Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <email address hidden>
dominique@Dominique-lucid:~$
Advice?