Do you also have the problem, that you sometimes get a messy gnome-panel  on your gnome powered Linux desktop after booting the system or adding another display to your configuration? Here's a quick fix for those situations.

Just restart gnome-panel:

$ killall gnome-panel

That should bring everything back to order. If not, try the hardcore way:

$ gconftool-2 --recursive-unset /apps/panel && killall gnome-panel &

This will reset your gnome-panels to the default values. However, you will have to add all your panel-shortcuts and programs again afterwards.