Top panel/menu bar empty after upgrade

[Baasha]

I have just done an automatic upgrade from 13.04 to 13.10. I am using the Gnome Classic desktop.

After the upgrade I find the top panel/menu bar is empty. That is, there is no Appllications, Places, Clock & Calendar.

When I am on the login screen the clock and settings gear are there, but after the login all I have is an empty black bar. I have tried rebooting several times, and I tried restarting lightdm, with no results.

Any suggestions would be welcome.

[ElvenWriter]

I have the same problem, it's not possible to add items to top panel menu bar. Alt+Right click in the panel show the usual item list window, but trying to add some item to the panel has no effect