Upgraded from 10.04 to 10.10 by mistake and am having problems with some of my programs. They either don't work or they disappear from view on the screen. The Repositories menu item in Synaptic Packages Manager is a case in point. The computer does nothing when I choose this item. I am locked out of unless I edit /etc/apt/sources.list. The rest of the application seems to work, however. Update Manager just flashes on screen then disappears without doing, as does Printing. How do I downgrade from a higher to a lower level repository? I need to downgrade from 10.10 to 10.04. Each time Ubuntu upgrades to 10.10 evil things happen and the operating system really gets messed up. I really do not want to have to erase and install my operating system all over again if I can help it.