To render my system useable after upgrading to 11.10, I had to abandon gnome and install the KDE window manager. This is mostly fine, but the desktop wallpaper slideshow works for a few minutes and then gets reset to the default (fixed kubuntu splash background). I can start up the slideshow again by right-clicking on the background and re-entering all the Desktop Settings, but then it just disappears again after a while. What could be causing this?

Oops!   What I failed to realize was that KDE apparently uses an independent wallpaper setting for each desktop. I have 12, so some were set to the slideshow but others were still set to the default. Being accustomed to one common wallpaper setting for all desktops, I misinterpreted this as a global reset. Sorry!