After my last update I was not able to visualize my upper panel on Ubuntu 10.04 Netbook. After some internet searches and tests I found these two solutions which were useful to me:

Solution A

– right click on the background and choose Change Desktop Background

– go to Visual Effects and click on Normal

Solution B

– ALT + F2 and when in Terminal type

gnome-panel

If you want to save the configuration and visualize the upper panel for the next time you use Ubuntu, please type in terminal:

gnome-session-save

I am sure there are better ways to solve this problem, so if you have suggestion you are free to comment this post. Thanks.