Probleme avec l'update

Bonjour,

mon Ubuntu fonctionne parfaitement bien, je n'ai aucun problème sauf lors d'une MAJ. Quand je fait un apt-get update, j'obtiens ceci :

Ign http://ppa.launchpad.net natty InRelease 
Ign http://security.ubuntu.com natty-security InRelease                         
Ign http://archive.canonical.com natty InRelease                                
Ign http://extras.ubuntu.com natty InRelease                                    
Ign http://fr.archive.ubuntu.com natty InRelease                                
Ign http://fr.archive.ubuntu.com natty-updates InRelease                        
Atteint http://ppa.launchpad.net natty Release.gpg                              
Atteint http://security.ubuntu.com natty-security Release.gpg                   
Atteint http://archive.canonical.com natty Release.gpg                          
Atteint http://extras.ubuntu.com natty Release.gpg                              
Ign http://fr.archive.ubuntu.com natty-backports InRelease                      
Atteint http://fr.archive.ubuntu.com natty Release.gpg                          
Atteint http://ppa.launchpad.net natty Release                                  
Atteint http://security.ubuntu.com natty-security Release                       
Atteint http://archive.canonical.com natty Release                              
Atteint http://extras.ubuntu.com natty Release                                  
Atteint http://fr.archive.ubuntu.com natty-updates Release.gpg                  
Atteint http://ppa.launchpad.net natty/main Sources                             
Atteint http://security.ubuntu.com natty-security/main Sources                  
Atteint http://fr.archive.ubuntu.com natty-backports Release.gpg                
Atteint http://archive.canonical.com natty/partner Sources                      
Atteint http://extras.ubuntu.com natty/main Sources                             
Atteint http://ppa.launchpad.net natty/main amd64 Packages                      
Ign http://ppa.launchpad.net natty/main TranslationIndex                        
Atteint http://security.ubuntu.com natty-security/restricted Sources            
Atteint http://security.ubuntu.com natty-security/universe Sources              
Atteint http://security.ubuntu.com natty-security/multiverse Sources            
Atteint http://security.ubuntu.com natty-security/main amd64 Packages           
Atteint http://security.ubuntu.com natty-security/restricted amd64 Packages     
Atteint http://fr.archive.ubuntu.com natty Release                              
Atteint http://archive.canonical.com natty/partner amd64 Packages               
Ign http://archive.canonical.com natty/partner TranslationIndex                 
Atteint http://extras.ubuntu.com natty/main amd64 Packages                      
Ign http://extras.ubuntu.com natty/main TranslationIndex                        
Atteint http://security.ubuntu.com natty-security/universe amd64 Packages       
Atteint http://security.ubuntu.com natty-security/multiverse amd64 Packages     
Ign http://security.ubuntu.com natty-security/main TranslationIndex             
Ign http://security.ubuntu.com natty-security/multiverse TranslationIndex       
Ign http://security.ubuntu.com natty-security/restricted TranslationIndex       
Atteint http://fr.archive.ubuntu.com natty-updates Release                      
Ign http://security.ubuntu.com natty-security/universe TranslationIndex         
Atteint http://fr.archive.ubuntu.com natty-backports Release                    
Atteint http://fr.archive.ubuntu.com natty/main Sources                         
Atteint http://fr.archive.ubuntu.com natty/restricted Sources                   
Atteint http://fr.archive.ubuntu.com natty/universe Sources                     
Atteint http://fr.archive.ubuntu.com natty/multiverse Sources                   
Atteint http://fr.archive.ubuntu.com natty/main amd64 Packages                  
Atteint http://fr.archive.ubuntu.com natty/restricted amd64 Packages            
Atteint http://fr.archive.ubuntu.com natty/universe amd64 Packages              
Atteint http://fr.archive.ubuntu.com natty/multiverse amd64 Packages            
Ign http://fr.archive.ubuntu.com natty/main TranslationIndex                    
Ign http://fr.archive.ubuntu.com natty/multiverse TranslationIndex              
Ign http://fr.archive.ubuntu.com natty/restricted TranslationIndex              
Ign http://fr.archive.ubuntu.com natty/universe TranslationIndex                
Atteint http://fr.archive.ubuntu.com natty-updates/main Sources                 
Atteint http://fr.archive.ubuntu.com natty-updates/restricted Sources           
Atteint http://fr.archive.ubuntu.com natty-updates/universe Sources             
Atteint http://fr.archive.ubuntu.com natty-updates/multiverse Sources           
Atteint http://fr.archive.ubuntu.com natty-updates/main amd64 Packages          
Atteint http://fr.archive.ubuntu.com natty-updates/restricted amd64 Packages    
Atteint http://fr.archive.ubuntu.com natty-updates/universe amd64 Packages      
Atteint http://fr.archive.ubuntu.com natty-updates/multiverse amd64 Packages    
Ign http://fr.archive.ubuntu.com natty-updates/main TranslationIndex            
Ign http://fr.archive.ubuntu.com natty-updates/multiverse TranslationIndex      
Ign http://fr.archive.ubuntu.com natty-updates/restricted TranslationIndex      
Ign http://fr.archive.ubuntu.com natty-updates/universe TranslationIndex        
Atteint http://fr.archive.ubuntu.com natty-backports/main Sources               
Atteint http://fr.archive.ubuntu.com natty-backports/restricted Sources         
Atteint http://fr.archive.ubuntu.com natty-backports/universe Sources           
Atteint http://fr.archive.ubuntu.com natty-backports/multiverse Sources         
Atteint http://fr.archive.ubuntu.com natty-backports/main amd64 Packages        
Atteint http://fr.archive.ubuntu.com natty-backports/restricted amd64 Packages  
Atteint http://fr.archive.ubuntu.com natty-backports/universe amd64 Packages    
Atteint http://fr.archive.ubuntu.com natty-backports/multiverse amd64 Packages  
Ign http://fr.archive.ubuntu.com natty-backports/main TranslationIndex          
Ign http://fr.archive.ubuntu.com natty-backports/multiverse TranslationIndex    
Ign http://fr.archive.ubuntu.com natty-backports/restricted TranslationIndex    
Ign http://security.ubuntu.com natty-security/main Translation-fr_FR            
Ign http://security.ubuntu.com natty-security/main Translation-fr               
Ign http://security.ubuntu.com natty-security/main Translation-en               
Ign http://security.ubuntu.com natty-security/multiverse Translation-fr_FR      
Ign http://security.ubuntu.com natty-security/multiverse Translation-fr         
Ign http://security.ubuntu.com natty-security/multiverse Translation-en         
Ign http://security.ubuntu.com natty-security/restricted Translation-fr_FR      
Ign http://fr.archive.ubuntu.com natty-backports/universe TranslationIndex      
Atteint http://fr.archive.ubuntu.com natty/main Translation-fr                  
Ign http://security.ubuntu.com natty-security/restricted Translation-fr         
Ign http://security.ubuntu.com natty-security/restricted Translation-en         
Atteint http://fr.archive.ubuntu.com natty/multiverse Translation-fr            
Atteint http://fr.archive.ubuntu.com natty/restricted Translation-fr            
Ign http://security.ubuntu.com natty-security/universe Translation-fr_FR        
Ign http://security.ubuntu.com natty-security/universe Translation-fr           
Ign http://security.ubuntu.com natty-security/universe Translation-en           
Atteint http://fr.archive.ubuntu.com natty/universe Translation-fr              
Ign http://ppa.launchpad.net natty/main Translation-fr_FR                       
Ign http://archive.canonical.com natty/partner Translation-fr_FR                
Ign http://extras.ubuntu.com natty/main Translation-fr_FR                       
Ign http://ppa.launchpad.net natty/main Translation-fr                          
Ign http://archive.canonical.com natty/partner Translation-fr                   
Ign http://extras.ubuntu.com natty/main Translation-fr                          
Ign http://ppa.launchpad.net natty/main Translation-en                          
Ign http://archive.canonical.com natty/partner Translation-en                   
Ign http://extras.ubuntu.com natty/main Translation-en                          
Ign http://fr.archive.ubuntu.com natty/main Translation-fr_FR           
Ign http://fr.archive.ubuntu.com natty/main Translation-en 
Ign http://fr.archive.ubuntu.com natty/multiverse Translation-fr_FR 
Ign http://fr.archive.ubuntu.com natty/multiverse Translation-en 
Ign http://fr.archive.ubuntu.com natty/restricted Translation-fr_FR 
Ign http://fr.archive.ubuntu.com natty/restricted Translation-en 
Ign http://fr.archive.ubuntu.com natty/universe Translation-fr_FR 
Ign http://fr.archive.ubuntu.com natty/universe Translation-en 
Ign http://fr.archive.ubuntu.com natty-updates/main Translation-fr_FR 
Ign http://fr.archive.ubuntu.com natty-updates/main Translation-fr 
Ign http://fr.archive.ubuntu.com natty-updates/main Translation-en 
Ign http://fr.archive.ubuntu.com natty-updates/multiverse Translation-fr_FR 
Ign http://fr.archive.ubuntu.com natty-updates/multiverse Translation-fr 
Ign http://fr.archive.ubuntu.com natty-updates/multiverse Translation-en 
Ign http://fr.archive.ubuntu.com natty-updates/restricted Translation-fr_FR 
Ign http://fr.archive.ubuntu.com natty-updates/restricted Translation-fr 
Ign http://fr.archive.ubuntu.com natty-updates/restricted Translation-en 
Ign http://fr.archive.ubuntu.com natty-updates/universe Translation-fr_FR 
Ign http://fr.archive.ubuntu.com natty-updates/universe Translation-fr 
Ign http://fr.archive.ubuntu.com natty-updates/universe Translation-en 
Ign http://fr.archive.ubuntu.com natty-backports/main Translation-fr_FR 
Ign http://fr.archive.ubuntu.com natty-backports/main Translation-fr 
Ign http://fr.archive.ubuntu.com natty-backports/main Translation-en 
Ign http://fr.archive.ubuntu.com natty-backports/multiverse Translation-fr_FR 
Ign http://fr.archive.ubuntu.com natty-backports/multiverse Translation-fr 
Ign http://fr.archive.ubuntu.com natty-backports/multiverse Translation-en 
Ign http://fr.archive.ubuntu.com natty-backports/restricted Translation-fr_FR 
Ign http://fr.archive.ubuntu.com natty-backports/restricted Translation-fr 
Ign http://fr.archive.ubuntu.com natty-backports/restricted Translation-en 
Ign http://fr.archive.ubuntu.com natty-backports/universe Translation-fr_FR 
Ign http://fr.archive.ubuntu.com natty-backports/universe Translation-fr 
Ign http://fr.archive.ubuntu.com natty-backports/universe Translation-en

D'où cela peut-il venir ? je poste également mon dossier sources.list :

# deb cdrom:[Ubuntu 11.04 _Natty Narwhal_ - Release amd64 (20110427.1)]/ natty main restricted 

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to 
# newer versions of the distribution. 
deb http://fr.archive.ubuntu.com/ubuntu/ natty main restricted 
deb-src http://fr.archive.ubuntu.com/ubuntu/ natty main restricted 

## Major bug fix updates produced after the final release of the 
## distribution. 
deb http://fr.archive.ubuntu.com/ubuntu/ natty-updates main restricted 
deb-src http://fr.archive.ubuntu.com/ubuntu/ natty-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://fr.archive.ubuntu.com/ubuntu/ natty universe 
deb-src http://fr.archive.ubuntu.com/ubuntu/ natty universe 
deb http://fr.archive.ubuntu.com/ubuntu/ natty-updates universe 
deb-src http://fr.archive.ubuntu.com/ubuntu/ natty-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://fr.archive.ubuntu.com/ubuntu/ natty multiverse 
deb-src http://fr.archive.ubuntu.com/ubuntu/ natty multiverse 
deb http://fr.archive.ubuntu.com/ubuntu/ natty-updates multiverse 
deb-src http://fr.archive.ubuntu.com/ubuntu/ natty-updates multiverse 

## Uncomment the following two lines to add software from the 'backports' 
## repository. 
## 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://fr.archive.ubuntu.com/ubuntu/ natty-backports main restricted universe multiverse 
deb-src http://fr.archive.ubuntu.com/ubuntu/ natty-backports main restricted universe multiverse 

deb http://security.ubuntu.com/ubuntu natty-security main restricted 
deb-src http://security.ubuntu.com/ubuntu natty-security main restricted 
deb http://security.ubuntu.com/ubuntu natty-security universe 
deb-src http://security.ubuntu.com/ubuntu natty-security universe 
deb http://security.ubuntu.com/ubuntu natty-security multiverse 
deb-src http://security.ubuntu.com/ubuntu natty-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 natty partner 
deb-src http://archive.canonical.com/ubuntu natty 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 natty main 
deb-src http://extras.ubuntu.com/ubuntu natty main

Merci d'avance