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I have this error:

W: Failed to fetch cdrom://Ubuntu 12.04.3 LTS _Precise Pangolin_ - Release amd64 (20130820.1)/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 bzip2:/var/lib/apt/lists/partial/jo.archive.ubuntu.com_ubuntu_dists_precise-updates_main_binary-amd64_Packages  Hash Sum mismatch

E: Some index files failed to download. They have been ignored, or old ones used instead.
share|improve this question

That is not an error, the "W" is a warning.

This message can be ignored, it is telling you Ubuntu is looking for packages on the "cdrom", but there is no cdrom on your system.

Remove (uncheck) the CDROM from your sources:

enter image description here

See for additional information.

share|improve this answer
it is unchecked – the Lord of the Doom Jan 14 '14 at 19:05
OK, try sudo apt-get update – bodhi.zazen Jan 14 '14 at 19:05
i tried it & i have the same warning – the Lord of the Doom Jan 14 '14 at 19:18
Post the exact output you are getting as well as your sources. The second warning usually comes from connectivity problems, try another mirror or try again later today. – bodhi.zazen Jan 14 '14 at 19:22

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