I have the following issue on Ubuntu 12.04 LTS on a 64-bit machine:
Whenever I try to update the aptitude repos, the update will strangely fail with a i386-related error. I assume that this shouldn't be happening on a 64-bit system.

root@liv-HP-Compaq-dc7900:/home/liv# apt-get update

Ign file: apt-build Release.gpg

Get:1 file: apt-build Release [107 B]                                          

Ign file: apt-build/main TranslationIndex                                      

Err file: apt-build/main i386 Packages                                         

  File not found

[..]

W: Failed to fetch file:/var/cache/apt-build/repository/dists/apt-build/main/binary-i386/Packages  File not found



E: Some index files failed to download. They have been ignored, or old ones used instead.

I tried to restore status-old with no luck:

sudo cp /var/lib/dpkg/status-old /var/lib/dpkg/status

I also tried:

root@liv-HP-Compaq-dc7900:/home/liv# apt-get -f install

Reading package lists... Done

Building dependency tree       

Reading state information... Done

0 upgraded, 0 newly installed, 0 to remove and 90 not upgraded.

But it doesn't seem to do or report anything useful. Each subsequent apt-get update ends up in an error.

For the record, my /etc/apt/sources.list file looks like this:

# deb cdrom:[Xubuntu 12.04 LTS _Precise Pangolin_ - Release amd64 (20120425)]/ dists/precise/main/binary-i386/



# deb cdrom:[Xubuntu 12.04 LTS _Precise Pangolin_ - Release amd64 (20120425)]/ dists/precise/multiverse/binary-i386/

# deb cdrom:[Xubuntu 12.04 LTS _Precise Pangolin_ - Release amd64 (20120425)]/ dists/precise/restricted/binary-i386/

# deb cdrom:[Xubuntu 12.04 LTS _Precise Pangolin_ - Release amd64 (20120425)]/ dists/precise/universe/binary-i386/

# deb cdrom:[Xubuntu 12.04 LTS _Precise Pangolin_ - Release amd64 (20120425)]/ precise main multiverse restricted universe



# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to

# newer versions of the distribution.

deb http://nl.archive.ubuntu.com/ubuntu/ precise main restricted

deb-src http://nl.archive.ubuntu.com/ubuntu/ precise main restricted



## Major bug fix updates produced after the final release of the

## distribution.

deb http://nl.archive.ubuntu.com/ubuntu/ precise-updates main restricted

deb-src http://nl.archive.ubuntu.com/ubuntu/ precise-updates main restricted



## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu

## team. Also, please note that software in universe WILL NOT receive any

## review or updates from the Ubuntu security team.

deb http://nl.archive.ubuntu.com/ubuntu/ precise universe

deb-src http://nl.archive.ubuntu.com/ubuntu/ precise universe

deb http://nl.archive.ubuntu.com/ubuntu/ precise-updates universe

deb-src http://nl.archive.ubuntu.com/ubuntu/ precise-updates universe



## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu 

## team, and may not be under a free licence. Please satisfy yourself as to 

## your rights to use the software. Also, please note that software in 

## multiverse WILL NOT receive any review or updates from the Ubuntu

## security team.

deb http://nl.archive.ubuntu.com/ubuntu/ precise multiverse

deb-src http://nl.archive.ubuntu.com/ubuntu/ precise multiverse

deb http://nl.archive.ubuntu.com/ubuntu/ precise-updates multiverse

deb-src http://nl.archive.ubuntu.com/ubuntu/ precise-updates multiverse



## N.B. software from this repository may not have been tested as

## extensively as that contained in the main release, although it includes

## newer versions of some applications which may provide useful features.

## Also, please note that software in backports WILL NOT receive any review

## or updates from the Ubuntu security team.

deb http://nl.archive.ubuntu.com/ubuntu/ precise-backports main restricted universe multiverse

deb-src http://nl.archive.ubuntu.com/ubuntu/ precise-backports main restricted universe multiverse



deb http://security.ubuntu.com/ubuntu precise-security main restricted

deb-src http://security.ubuntu.com/ubuntu precise-security main restricted

deb http://security.ubuntu.com/ubuntu precise-security universe

deb-src http://security.ubuntu.com/ubuntu precise-security universe

deb http://security.ubuntu.com/ubuntu precise-security multiverse

deb-src http://security.ubuntu.com/ubuntu precise-security multiverse



## Uncomment the following two lines to add software from Canonical's

## 'partner' repository.

## This software is not part of Ubuntu, but is offered by Canonical and the

## respective vendors as a service to Ubuntu users.

deb http://archive.canonical.com/ubuntu precise partner

# deb-src http://archive.canonical.com/ubuntu precise partner



## This software is not part of Ubuntu, but is offered by third-party

## developers who want to ship their latest software.

deb http://extras.ubuntu.com/ubuntu precise main

deb-src http://extras.ubuntu.com/ubuntu precise main

deb http://cran.at.r-project.org/bin/linux/ubuntu precise/

# deb-src http://cran.at.r-project.org/bin/linux/ubuntu precise/

# deb http://archive.canonical.com/ precise partner

# deb-src http://archive.canonical.com/ precise partner

And the kernel in use is:

liv@liv-HP-Compaq-dc7900:~$ uname -a

Linux liv-HP-Compaq-dc7900 3.2.0-57-generic #87-Ubuntu SMP Tue Nov 12 21:35:10 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

What is wrong and how can I fix it?