Error message:
Fetch failed: W:Failed to fetch cdrom://[Debian GNU/Linux 6.0.2.1 _Squeeze_ - Official amd64 NETINST Binary-1 20110628-12:58]/dists/squeeze/main/binary-amd64/Packages.gz  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 ftp://ftp.surfnet.nl/pub/os/Linux/distr/debian/dists/squeeze/updates/main/source/Sources.gz  Unable to fetch file, server said 'Failed to open file.  ' [IP: 192.87.102.43 21]
, W:Failed to fetch ftp://ftp.surfnet.nl/pub/os/Linux/distr/debian/dists/squeeze/updates/contrib/source/Sources.gz  Unable to fetch file, server said 'Failed to open file.  ' [IP: 192.87.102.43 21]
, W:Failed to fetch ftp://ftp.surfnet.nl/pub/os/Linux/distr/debian/dists/squeeze/updates/non-free/source/Sources.gz  Unable to fetch file, server said 'Failed to open file.  ' [IP: 192.87.102.43 21]
, E:Some index files failed to download, they have been ignored, or old ones used instead.