every time I run
sudo apt-get update I get an error:
W: Failed to fetch https://private-ppa.launchpad.net/commercial-ppa-uploaders/limbo/ubuntu/dists/precise/main/binary-i386/Packages The requested URL returned error: 401
This URL is not in my sources list nor do I know what I need from it, but Ubuntu's not updating without it. What can I do to fix it?