Ошибки при обновлении

[bureaua]

При обновлении начал выдавать ошибку...

user@PC:/var/lib/apt$ sudo apt-get update
Get:1 http://security.ubuntu.com precise-security Release.gpg [5,415 B]
Get:2 http://security.ubuntu.com precise-security Release [5,411 B]
Err http://security.ubuntu.com precise-security Release

Get:3 http://us.archive.ubuntu.com precise Release.gpg [5,408 B]
Get:4 http://us.archive.ubuntu.com precise-updates Release.gpg [5,416 B]
Get:5 http://us.archive.ubuntu.com precise-backports Release.gpg [5,418 B]
Get:6 http://us.archive.ubuntu.com precise Release [5,404 B]
Err http://us.archive.ubuntu.com precise Release

Get:7 http://us.archive.ubuntu.com precise-updates Release [5,412 B]
Err http://us.archive.ubuntu.com precise-updates Release

Get:8 http://us.archive.ubuntu.com precise-backports Release [5,414 B]
Err http://us.archive.ubuntu.com precise-backports Release

Fetched 43.3 kB in 1s (30.0 kB/s)
Reading package lists... Done
W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://security.ubuntu.com precise-security Release: The following signatures were invalid: NODATA 1 NODATA 2

W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://us.archive.ubuntu.com precise Release: The following signatures were invalid: NODATA 1 NODATA 2

W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://us.archive.ubuntu.com precise-updates Release: The following signatures were invalid: NODATA 1 NODATA 2

W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://us.archive.ubuntu.com precise-backports Release: The following signatures were invalid: NODATA 1 NODATA 2

W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/precise-security/Release

W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise/Release

W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-updates/Release

W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/precise-backports/Release

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

Поиски решений в сети не дали никакого результата...
Попробовать отключить "http://security.ubuntu.com precise-security Release"... Так веть пару дней назад все работало...
удаление раздела "/var/lib/apt.lists" и создание нового не помогло -- полезли новые ошибки...   
Идем далее

user@PC:/var/lib/apt$ sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be upgraded:
  bash
1 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 616 kB of archives.
After this operation, 12.3 kB disk space will be freed.
Do you want to continue [Y/n]? Y
Get:1 http://us.archive.ubuntu.com/ubuntu/ precise-updates/main bash i386 4.2-2ubuntu2.1 [616 kB]
Fetched 5,428 B in 0s (89.9 kB/s)
Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/b/bash/bash_4.2-2ubuntu2.1_i386.deb  Size mismatch
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?