Software updated failed

[JD]

This is the error message:

W:GPG error: http://repo.mate-desktop.org quantal InRelease: The 
following signatures couldn't be verified because the public key is not 
available: NO_PUBKEY 68980A0EA10B4DE8,
W:GPG error: http://packages.mate-desktop.org quantal Release: The 
following signatures couldn't be verified because the public key is not 
available: NO_PUBKEY 68980A0EA10B4DE8,
W:Failed to fetch cdrom://Ubuntu 12.04 LTS _Precise Pangolin_ - Release 
i386 (20120423)/dists/precise/main/binary-i386/Packages Please use 
apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot 
be used to add new CD-ROMs,
W:Failed to fetch cdrom://Ubuntu 12.04 LTS _Precise Pangolin_ - Release 
i386 (20120423)/dists/precise/restricted/binary-i386/Packages  Please 
use apt-cdrom to make this CD-ROM recognized by APT. apt-get update 
cannot be used to add new CD-ROMs,
E:Some index files failed to download. They have been ignored, or old 
ones used instead.

Question is why is it looking for
cdrom://Ubuntu 12.04 LTS _Precise Pangolin_ - Release i386 
(20120423)/dists/precise/restricted/binary-i386/Packages

since I am not running 12.04, but 12.10 (Quantal).

Perhaps I shouldnot have upgraded from 12.04 to 12.10 ????