Every once in a while I can't install packages in Ubuntu 11.04. I'll try to run the software center and it and it will pop up then disappear. If I call it from the command line it says it seg-faults. And then trying to install anything from the command line I get this:
sudo apt-get install pdftk Reading package lists... Done
And thats all I get for anything I try. Usually restarting fixes the problem but its very annoying.