I had this problem and changing the software source server fixed it for me. System -> Admin -> Software Sources.
http://ubuntuforums.org/showthread.php?t=1339490&page=2 -- Untrusted packages not installable https://bugs.launchpad.net/bugs/464101 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
