Why is this still happening?

[MakOwner]

Again. And Again.

<code> GPG error: http://archive.ubuntu.com precise Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <ftpmaster@ubuntu.com>
</code>

[dannyboy79]

try the following commands,

sudo mv /var/lib/apt/lists /var/lib/apt/lists.old

sudo mkdir -p /var/lib/apt/lists/partial

sudo aptitude update