I think it's related to this bug http://bugs.kde.org/show_bug.cgi?id=158779
I reported this bug to the kubuntu developers and they advised me to only submit the bug upstream at KDE
To check if that's the cause you should look for any .desktop files in your /usr/share/applications/ directory that have an invalid MimeType. In my case it was "MimeType=;" in Swiftfox.desktop
I think it's related to this bug http:// bugs.kde. org/show_ bug.cgi? id=158779 applications/ directory that have an invalid MimeType. In my case it was "MimeType=;" in Swiftfox.desktop
I reported this bug to the kubuntu developers and they advised me to only submit the bug upstream at KDE
To check if that's the cause you should look for any .desktop files in your /usr/share/