Comment 3 for bug 9863

I have this problem occasionally too - started when I upgraded to hoary.
Currently gnome-panel is version 2.9.3-0ubuntu1.

I almost always shut down my laptop instead of just logging out, so it couldn't
be that the gnome-panel is still running - this has happened on booting up from
power off.

Stopping gdm and restarting it didn't fix the problem. A reboot generally did
fix it.

Some times it looked like the panels didn't start at all - I had a blank panel
at the top and a blank panel at the bottom. Some times the bottom panel at least
had the "minimise all" button and the window list, but nothing else - no menus,
no trash applet, no notifier applets.