Hello everybody!
I cannot add any applet to any (top or bottom) panel, cannot delete any panel nor create a new panel. When I right-click on the panel the only options available are: Properties, Help or About panels.

[I cannot post an image because of spam prevention, so I'll do my best]
I can see when I right-click (bold means clickable):

• Add to panel
• Properties
• Delete this panel
• New panel
• Help
• About Panels

Trying to solve this I did what is usually suggested:

gconftool-2 –-recursive-unset /apps/panel # might be optional
rm -rf ~/.gconf/apps/panel
pkill gnome-panel

but I only got a nice empty panel (no Applications Places System, no clock, no shutdown button...) to which I couldn't add any applet, so I decided to take the default profiles in .gconf and .gconfd from a live CD and overwrite mines. Now we are back to the beginning.

I also have tried to lock completely the panel (with both gconf-editor and pessulus) and later unlock it completely but it didn't work.

Here is the system information:

$ lsb_release
Distributor ID: Ubuntu
Description: Ubuntu 10.04.2 LTS
Release: 10.04
Codename: lucid

Thank you very much.