Comment 12 for bug 53319

http://packages.freecontrib.org/plf/dists/dapper/multiverse/binary-i386/Packages.gz: 404 Not Found

From checking the website it seems that the repository list is changing often due to server migration/dns setup issues. But I'm not sure since I don't know much french.

http://blog.freecontrib.org/index.php/2006/07/23/26-nouveau-mainteneur-de-ubuntu-plf

says to set the repository to:

http://packages.freecontrib.org/ubuntu/plf/