fresh natty install i386 desktop. I get this errors:
Code: 
$ sudo apt-get updateIgn http://extras.ubuntu.com natty InReleaseIgn http://archive.ubuntu.com natty InReleaseIgn http://archive.ubuntu.com natty-updates InReleaseIgn http://archive.ubuntu.com natty-security InReleaseHit http://extras.ubuntu.com natty Release.gpgHit http://extras.ubuntu.com natty ReleaseErr http://archive.ubuntu.com natty Release.gpg  Bad header line [IP: 91.189.92.171 80]Ign http://archive.ubuntu.com natty-updates Release.gpgHit http://extras.ubuntu.com natty/main SourcesErr http://archive.ubuntu.com natty-security Release.gpg  Bad header line [IP: 91.189.92.171 80]Ign http://archive.ubuntu.com natty ReleaseIgn http://archive.ubuntu.com natty-updates ReleaseHit http://extras.ubuntu.com natty/main i386 PackagesIgn http://extras.ubuntu.com natty/main TranslationIndexGet:1 http://archive.ubuntu.com natty-security Release [31,4 kB]Err http://extras.ubuntu.com natty/main Translation-en_US  Bad header lineErr http://extras.ubuntu.com natty/main Translation-en     Bad header lineGet:2 http://archive.ubuntu.com natty-security Release [31,4 kB]                                                                                             Ign http://archive.ubuntu.com natty/main Sources/DiffIndexIgn http://archive.ubuntu.com natty/restricted Sources/DiffIndexIgn http://archive.ubuntu.com natty/universe Sources/DiffIndexIgn http://archive.ubuntu.com natty/multiverse Sources/DiffIndexIgn http://archive.ubuntu.com natty/main i386 Packages/DiffIndexIgn http://archive.ubuntu.com natty/restricted i386 Packages/DiffIndexIgn http://archive.ubuntu.com natty/universe i386 Packages/DiffIndexIgn http://archive.ubuntu.com natty/multiverse i386 Packages/DiffIndexIgn http://archive.ubuntu.com natty/main TranslationIndexIgn http://extras.ubuntu.com natty/main Translation-es                                                                                                       Ign http://archive.ubuntu.com natty/multiverse TranslationIndex                                                                                              Ign http://archive.ubuntu.com natty/restricted TranslationIndexIgn http://archive.ubuntu.com natty/universe TranslationIndexIgn http://archive.ubuntu.com natty-updates/main Sources/DiffIndexIgn http://archive.ubuntu.com natty-updates/restricted Sources/DiffIndexIgn http://archive.ubuntu.com natty-updates/universe Sources/DiffIndexIgn http://archive.ubuntu.com natty-updates/multiverse Sources/DiffIndexIgn http://archive.ubuntu.com natty-updates/main i386 Packages/DiffIndexIgn http://archive.ubuntu.com natty-updates/restricted i386 Packages/DiffIndexIgn http://archive.ubuntu.com natty-updates/universe i386 Packages/DiffIndexIgn http://archive.ubuntu.com natty-updates/multiverse i386 Packages/DiffIndexIgn http://archive.ubuntu.com natty-updates/main TranslationIndexIgn http://archive.ubuntu.com natty-updates/multiverse TranslationIndexIgn http://archive.ubuntu.com natty-updates/restricted TranslationIndexIgn http://archive.ubuntu.com natty-updates/universe TranslationIndexIgn http://archive.ubuntu.com natty-security/main Sources/DiffIndexIgn http://archive.ubuntu.com natty-security/restricted Sources/DiffIndexIgn http://archive.ubuntu.com natty-security/universe Sources/DiffIndexIgn http://archive.ubuntu.com natty-security/multiverse Sources/DiffIndexIgn http://archive.ubuntu.com natty-security/main i386 Packages/DiffIndexIgn http://archive.ubuntu.com natty-security/restricted i386 Packages/DiffIndexIgn http://archive.ubuntu.com natty-security/universe i386 Packages/DiffIndexIgn http://archive.ubuntu.com natty-security/multiverse i386 Packages/DiffIndexIgn http://archive.ubuntu.com natty-security/main TranslationIndexIgn http://archive.ubuntu.com natty-security/multiverse TranslationIndexIgn http://archive.ubuntu.com natty-security/restricted TranslationIndexIgn http://archive.ubuntu.com natty-security/universe TranslationIndexHit http://archive.ubuntu.com natty/main SourcesHit http://archive.ubuntu.com natty/restricted SourcesHit http://archive.ubuntu.com natty/universe SourcesHit http://archive.ubuntu.com natty/multiverse SourcesHit http://archive.ubuntu.com natty/main i386 PackagesHit http://archive.ubuntu.com natty/restricted i386 PackagesHit http://archive.ubuntu.com natty/universe i386 PackagesHit http://archive.ubuntu.com natty/multiverse i386 PackagesHit http://archive.ubuntu.com natty/main Translation-esHit http://archive.ubuntu.com natty/multiverse Translation-esHit http://archive.ubuntu.com natty/restricted Translation-esHit http://archive.ubuntu.com natty/universe Translation-esHit http://archive.ubuntu.com natty-updates/main SourcesHit http://archive.ubuntu.com natty-updates/restricted SourcesHit http://archive.ubuntu.com natty-updates/universe SourcesHit http://archive.ubuntu.com natty-updates/multiverse SourcesHit http://archive.ubuntu.com natty-updates/main i386 PackagesHit http://archive.ubuntu.com natty-updates/restricted i386 PackagesHit http://archive.ubuntu.com natty-updates/universe i386 PackagesHit http://archive.ubuntu.com natty-updates/multiverse i386 PackagesHit http://archive.ubuntu.com natty-security/main SourcesHit http://archive.ubuntu.com natty-security/restricted SourcesHit http://archive.ubuntu.com natty-security/universe SourcesHit http://archive.ubuntu.com natty-security/multiverse SourcesHit http://archive.ubuntu.com natty-security/main i386 PackagesHit http://archive.ubuntu.com natty-security/restricted i386 PackagesHit http://archive.ubuntu.com natty-security/universe i386 PackagesHit http://archive.ubuntu.com natty-security/multiverse i386 PackagesIgn http://archive.ubuntu.com natty/main Translation-en_USIgn http://archive.ubuntu.com natty/main Translation-enIgn http://archive.ubuntu.com natty/multiverse Translation-en_USIgn http://archive.ubuntu.com natty/multiverse Translation-enIgn http://archive.ubuntu.com natty/restricted Translation-en_USIgn http://archive.ubuntu.com natty/restricted Translation-enIgn http://archive.ubuntu.com natty/universe Translation-en_USIgn http://archive.ubuntu.com natty/universe Translation-enIgn http://archive.ubuntu.com natty-updates/main Translation-en_USIgn http://archive.ubuntu.com natty-updates/main Translation-enIgn http://archive.ubuntu.com natty-updates/main Translation-esIgn http://archive.ubuntu.com natty-updates/multiverse Translation-en_USIgn http://archive.ubuntu.com natty-updates/multiverse Translation-enIgn http://archive.ubuntu.com natty-updates/multiverse Translation-esIgn http://archive.ubuntu.com natty-updates/restricted Translation-en_USIgn http://archive.ubuntu.com natty-updates/restricted Translation-enIgn http://archive.ubuntu.com natty-updates/restricted Translation-esIgn http://archive.ubuntu.com natty-updates/universe Translation-en_USIgn http://archive.ubuntu.com natty-updates/universe Translation-enIgn http://archive.ubuntu.com natty-updates/universe Translation-esIgn http://archive.ubuntu.com natty-security/main Translation-en_USIgn http://archive.ubuntu.com natty-security/main Translation-enIgn http://archive.ubuntu.com natty-security/main Translation-esIgn http://archive.ubuntu.com natty-security/multiverse Translation-en_USIgn http://archive.ubuntu.com natty-security/multiverse Translation-enIgn http://archive.ubuntu.com natty-security/multiverse Translation-esIgn http://archive.ubuntu.com natty-security/restricted Translation-en_USIgn http://archive.ubuntu.com natty-security/restricted Translation-enIgn http://archive.ubuntu.com natty-security/restricted Translation-esIgn http://archive.ubuntu.com natty-security/universe Translation-en_USIgn http://archive.ubuntu.com natty-security/universe Translation-enIgn http://archive.ubuntu.com natty-security/universe Translation-esFetched 31,4 kB in 1min 21s (384 B/s)W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/natty/Release.gpg  Bad header line [IP: 91.189.92.171 80]W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/natty-security/Release.gpg  Bad header line [IP: 91.189.92.171 80]W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/natty/main/i18n/Translation-en_US  Bad header lineW: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/natty/main/i18n/Translation-en  Bad header lineE: Some index files failed to download. They have been ignored, or old ones used instead.
I followed this solution found in google:
Code: 
$ cd /var/lib/apt$ sudo mv lists lists.old$ sudo mkdir -p lists/partial$ sudo apt-get update
but nothing, so i reinsatalled from another iso to see if that was the problem.. its the same. I dont know what to do. 
I also set default keys with the button found in authentification in sources dialog... and changed sources from main to my local mirros. Its the same...
i hope the next release is better, because natty has been a huge hindrance from the very beginning 
any help please? Its frustrating...