I've noticed I can't check for new updates, neither via terminal nor update manager. For example, update manager throws error saying something like "failed to download repository information. check your internet connection". Details are the following:
W:Failed to fetch http://ppa.launchpad.net/slicer/ppa/ubuntu/dists/precise/main/source/Sources 404 Not Found , W:Failed to fetch http://ppa.launchpad.net/slicer/ppa/ubuntu/dists/precise/main/binary-i386/Packages 404 Not Found , E:Some index files failed to download. They have been ignored, or old ones used instead.
I did a bit of googling, still couldn't find any solution :/