Problem with gnome-panel on Sid

[José Luis Segura Lucas <josel.segura@gmx.es>]

Hello!

I'm using Debian sid on several computers without any problem, but 
yesterday I boot one od them, recently updated and I have a lot of 
problem with gnome panels.

I usually had two panels (top and bottom), but when I started my gnome 
session, I can't see any of them.

When I press Alt+F1 the menu, and the entire top panel, is shown. The 
bottom panel is not shown, but if I maximize a Window, the space for the 
panel is still there. If I press the mouse right button in this space, I 
get the usual response of the desktop (change wallpaper, create 
folder...) instead the panel menu.

Today, with a second screen, I have a strange left-panel on it. It 
doesn't allow to add any applet, and if I look at its properties, I can 
see that is configured on the right side (it is shown on the left of the 
second screen).

Are somebody having a similar problem?
How can I check what upgraded package are causing the problem?
Can it be a problem with the Gnome3 packages recently added to sid?

Thanks in advance and best regards :-)