I copied the apt source directory from /var/cache/apt/archives/ on my laptop (11.10) to my work PC (11.10). I then removed /var/lib/apt/lists/*.

Now when I try to update my pc from the terminal, it shows "Failed to fetch" errors. If f use the Ubuntu update manager to install updates, it says: "waiting for unattended-upgrade to exit", but no update happens. Now it won't update anything.