after remove zeitgeist, there is no unity in Ubuntu

view story

http://askubuntu.com – Because zeitgeist continuously access the hard disk, I removed zeitgeist package completely. After that, when trying to log into Ubuntu, there is no more unity option, only Genome, Genome (no effects), etc. And even Genome doesn't work normal. Say pressing tab doesn't switch window, cannot open folder in the explorer. I tried to reinstall zeitgeist. The problem remains. When I run unity --reset in Genome session, the sidebar appears, the unity seems back. But if I close the command window that runs "unity --reset", the unity disappears. And I still don't have the option to log into unity next (HowTos)