I had this same problem. My solution was to switch to KPackage, which I find easier to use.
In terms of fixing your media, look at the man pages on "urpmi", "urpmi.addmedia", "urpmi.removemedia", "urpmi.update", and so on. I found that removing all my sources and then re-adding them did the trick. (Actually, when I updated urpmi, all my sources were wiped clean, so I HAD to re-add them.)