Every time I check for updates I get a message saying:

"Failed to download repository information"

Check your Internet connection.

Details:
W:Failed to fetch http://ppa.launchpad.net/pmcenery/pp...source/Sources 404 Not Found
, W:Failed to fetch http://ppa.launchpad.net/pmcenery/pp...-i386/Packages 404 Not Found
, E:Some index files failed to download. They have been ignored, or old ones used instead.

I'm still new to Linux. What is this and how can I fix it?