I suspect this is a self-inflicted wound, but not sure how I did it - maybe from updating PMS from a web client (if that is possible).
OMV's update manager now fails for me and I have traced the issue to the content of the file /etc/apt/sources.list.d/plexmediaserver.list which is: deb http://plex.r.worldssl.net/PlexMediaServer/ubuntu-repo lucid main
What is the content of this file supposed to be? Any suggestions on how this happened?