I have been using Ubuntu 11.10 for a few months. Recently am getting problems with installation of any new softwares. Even thought the internet connection is fine, it shows me the following message:

"Failed to download packages. Check you internet connection"

and following that error a pop up window appears repeatedly with the following message until I close the Ubuntu Software Center.

"Requires installation of untrusted packages. The action would require the installation of packages from not authenticated sources."

It would be greatly helpful, if anyone guides me to fix this problem at the earliest.

NOTE: I get may errors while trying to update the system from Terminal like "Something wicked has happened. Failed to fetch...".

Kindly offer your suggestions.

Hi,

in order to help you we need some more information.

Please post your /etc/apt/sources.list and any files in /etc/apt/sources.list.d/ and the out of the following two commands
Evo2.