To fix it, just type in the command prompt:
cp /etc/xdg/menus/applications.menu ~/.config/menus/
Updated
A much better way found here:
gconftool-2 --recursive-unset /apps/panel
To fix it, just type in the command prompt:
cp /etc/xdg/menus/applications.menu ~/.config/menus/
Updated
A much better way found here:
gconftool-2 --recursive-unset /apps/panel