update manager failed to download repository information

[Humphrey van Polanen Petel]

Update manager reports
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W:Failed to fetch http://au.archive.ubuntu.com/ubuntu/dists/precise-backports/main/source/Sources 406 Not Acceptable
, W:Failed to fetch gzip:/var/lib/apt/lists/partial/au.archive.ubuntu.com_ubuntu_dists_precise-backports_universe_source_Sources Hash Sum mismatch
, W:Failed to fetch gzip:/var/lib/apt/lists/partial/au.archive.ubuntu.com_ubuntu_dists_precise-backports_multiverse_source_Sources Hash Sum mismatch
, W:Failed to fetch http://au.archive.ubuntu.com/ubuntu/dists/precise-backports/main/binary-amd64/Packages 406 Not Acceptable
, W:Failed to fetch http://au.archive.ubuntu.com/ubuntu/dists/precise-backports/restricted/binary-amd64/Packages 406 Not Acceptable
, W:Failed to fetch gzip:/var/lib/apt/lists/partial/au.archive.ubuntu.com_ubuntu_dists_precise-backports_universe_binary-amd64_Packages Hash Sum mismatch
, W:Failed to fetch http://au.archive.ubuntu.com/ubuntu/dists/precise-backports/multiverse/binary-amd64/Packages 406 Not Acceptable
, W:Failed to fetch http://au.archive.ubuntu.com/ubuntu/dists/precise-backports/main/binary-i386/Packages 406 Not Acceptable
, W:Failed to fetch http://au.archive.ubuntu.com/ubuntu/dists/precise-backports/restricted/binary-i386/Packages 406 Not Acceptable
, W:Failed to fetch gzip:/var/lib/apt/lists/partial/au.archive.ubuntu.com_ubuntu_dists_precise-backports_universe_binary-i386_Packages Hash Sum mismatch
, E:Some index files failed to download. They have been ignored, or old ones used instead.

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ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: update-manager 1:0.156.14.11
ProcVersionSignature: Ubuntu 3.2.0-51.77-generic 3.2.48
Uname: Linux 3.2.0-51-generic x86_64
ApportVersion: 2.0.1-0ubuntu17.3
Architecture: amd64
Date: Wed Jul 31 11:21:13 2013
ExecutablePath: /usr/bin/update-manager
GsettingsChanges:
 com.ubuntu.update-manager first-run false
 com.ubuntu.update-manager launch-time 1375233546
 com.ubuntu.update-manager show-details true
 com.ubuntu.update-manager window-height 604
 com.ubuntu.update-manager window-width 600
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
InterpreterPath: /usr/bin/python2.7
MarkForUpload: True
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en_AU:en
 PATH=(custom, user)
 LANG=en_AU.UTF-8
 SHELL=/bin/bash
SourcePackage: update-manager
UpgradeStatus: No upgrade log present (probably fresh install)