Comment 10 for bug 915235

This what I did to get Muon Software Center to work. It's not perfect, but it does work - no crashes so far...:
Open Muon Package Manager --> Settings --> Configure Software Sources --> Password
Then, on the Kubuntu Software tab ( first page), "unclick" <Proprietary drivers for devices (restricted)>, followed by unclicking both <Software restricted by copyright or legal issues (multiverse)> and <Source Code>. Next tab, "Other Software", make sure nothing in this section is selected. Next tab, "Statistics", make sure <Submit statistical information> is not selected. Close and allow Muon Package Manager to refresh it's sources.
Now, right click the K-Menu button and select "Edit Applications". Find Muon Software Center in the System sub-menu. Change the command (on the right side of the screen) to "muon-installer" (without the quotes). Click Save and reboot. the Muon Software Center should be working.
It's an awful lot of work to get something that did work "out of the box" to work in a sort of satisfactory way.