Ubiquity detect a network problem, and generate a broken sources.list

Using Lubuntu Desktop amd64 (20111010.1)
Ubiquity starts to display the message that it can be updated, be the 2.8.6 is already on the system. After, it finishes the installation, but it detects in the end a network problem, that should be solved on the installed system. When I reboot, the network is OK, but the sources.list contains some lines which generate errors on "apt-get update" :

deb cdrom:[Lubuntu 11.10 _Oneiric Ocelot_ - Release amd64 (20111010.1)]/ dists/oneiric/main/binary-i386/

deb cdrom:[Lubuntu 11.10 _Oneiric Ocelot_ - Release amd64 (20111010.1)]/ oneiric main multiverse restricted universe

On an installation done by alternate ISO, those lines are commented.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: ubiquity (not installed)
ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4
Uname: Linux 3.0.0-12-generic x86_64
ApportVersion: 1.23-0ubuntu3
Architecture: amd64
Date: Tue Oct 11 02:33:07 2011
ProcEnviron:
 LANG=fr_FR.UTF-8
 SHELL=/bin/bash
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)