I receive the following error message when starting yumex after installing the linva repository.
failure: repodata/repomd.xml from livna: [Errno 256] No more mirrors to try.
http://rpm.livna.org/repo/23/i386/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found
http://ftp-stud.fht-esslingen.de/pub/Mirrors/rpm.livna.org/repo/23/i386/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found
ftp://mirrors.tummy.com/pub/rpm.livna.org/repo/23/i386/repodata/repomd.xml: [Errno 14] FTP Error 550 - Server denied you to change to the given directory
http://wftp.tu-chemnitz.de/pub/linux/livna/repo/23/i386/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found

You can try starting 'yumex -n' from a command line
and deselecting the repositories causing problems
and try again.
Running yumex -n --root from the command line works.