i had the same problem on KUbuntu 9.10, so i tried the list of commands suggested in the link below for the vanilla 8.10...
http://www.watchingthenet.com/restor...-settings.html
oddly, the suggestion ends with just pkill gnome-panel
this makes little sense as you are not restoring the panel afterward, so i typed gnome-panel into the terminal afterward and only then did both the top and bottom panels reappear