Error during update

[killboymota]

im using ubuntu 11.04. I already changed servers and nothing happened. I had not edited the sources.list but made a test to get the best server and nothing changed. thanks


Error During Update:
A problem occurred during the update. This is usually some sort of network problem, please check your network connection and retry.

W:Failed to fetch http://ubuntu-archive.mirrors.proxad.net/ubuntu/dists/natty/Release Unable to find expected entry non-free/source/Sources in Meta-index file (malformed Release file?)
, W:Failed to fetch http://archive.canonical.com/ubuntu/dists/natty/Release Unable to find expected entry non-free/source/Sources in Meta-index file (malformed Release file?)
, W:Failed to fetch http://extras.ubuntu.com/ubuntu/dists/natty/Release Unable to find expected entry non-free/source/Sources in Meta-index file (malformed Release file?)
, W:Failed to fetch http://ubuntu-archive.mirrors.proxad.net/ubuntu/dists/natty-updates/Release Unable to find expected entry non-free/source/Sources in Meta-index file (malformed Release file?)
, W:Failed to fetch http://ubuntu-archive.mirrors.proxad.net/ubuntu/dists/natty-backports/Release Unable to find expected entry non-free/source/Sources in Meta-index file (malformed Release file?)
, W:Failed to fetch http://ubuntu-archive.mirrors.proxad.net/ubuntu/dists/natty-security/Release Unable to find expected entry non-free/source/Sources in Meta-index file (malformed Release file?)
, E:Some index files failed to download, they have been ignored, or old ones used instead.

[Frogs Hair]

You could try these commands , another user was having the same problem two days ago and tried changing the server also .

sudo dpkg -reconfigure -a

sudo apt-get update

sudo apt-get upgrade