I did a custom install...chose KDE & Gnome support. Machine defaults to gnome as usual. This is OK. Open up an xterm & type "switchdesk"...errors with exec: switchdesk-gnome: not found.
when you did the custom install, you missed the switchdesk-gnome package. I have fixed switchdesk to not report an error for the next release, but the real fix for now is to install that package. Then your problem will go away.