using Ubuntu Software Center in 11.10 seems to be impossible to reload. For example, when I go to Software Sources and activate the Universe repo, USC does not automatically reload and so activate the Universe Repo. And I can find no "Reload" button as exists in synaptic. But on a clean install I can't install synaptic because I can't get the Universe repo activated cause I don't know how to get USC to reload.
I wish synaptic was kept in the Main repo.
Open a terminal (you can do ALT+F2 and type
gnome-terminal
) then type :Then type your password and wait until it is finished. Once it is finished you can close the terminal and reopen the Ubuntu Software Center.
There should be a way to do it without opening a terminal but I don't have 11.10 so I can't search for it.
You can always run the update manager and check for updates before installing software. That might be a good practice in any case. That will update all your sources.