I suggest you fix your sources.list so you won't see those warnings anymore. In terminal
sudo epad /etc/apt/sources.list
Now find lines with the word lucid and place a # in front of that line so they are commented out. Save the file and close epad. Next run
sudo apt-get update sudo apt-get dist-upgrade
In case you still have errors of some kind please report them here with details about the error.
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