After upgrading to 14.04 LTS, my gnome-flashback session starts, but without the top and bottom panels.
Logging with compiz, I can use CTRL+SHIFT+T to start a terminal and run "gnome-panel", which starts both panels. I'm using this workaround, but it is very annoying to login without the panels.
.xession-errors shows nothing related to gnome-flahback, just stuff like this:
init: indicator-bluetooth main process ended, respawning init: indicator-bluetooth respawning too fast, stopped