Run this in the terminal
sudo aptitude update

Please post what the out put is. I think it just may be a edit or two in the
/etc/apt/sources.list

If you find the line that causes the error go into it and put 2 ## in font of
the line. It tells the system to ignore it. If the update runs fine after that.
Then it will be safe if you wish to delete.

gksudo gedit /etc/apt/sources.list