Comment 34 for bug 414181

The faulty behaviour will be because the packages list is outdated, and could be reproduced like this:

1. From the application "software sources", change the update server.
2. Try to update the system using the "update manager" application.

Could you update the system doing this? If not, try this:

1. In the application "terminal", write "sudo apt-get update"
2. Try to update the system using the "update manager" application.

Does it work now? I'm all right this is the origin of the bug? because it happened many time ago for me.