This morning I logged in (after hibernate) and got a different theme on the desktop. Different colors, fonts, icons, whole deal. This has happened once or twice before and has fixed itself on the next log-in.
Also, Ctrl-Alt-Del to log out doesn’t work. I don’t know if that’s because of the theme change problem or because I suspended while in this session (which breaks middle mouse button scrolling).
Update: Logging out and back in fixed the theme and the Ctrl-Alt-Del key log-out sequence and middle mouse button scrolling.