As shown by the second screenshot, I have now managed to reproduce the bug in a predictable way. I have restored the original configuration running the commands illustrated here (http://www.watchingthenet.com/restore-panels-in-ubuntu-back-to-their-default-settings.html), then I modified the top panel (launchbar). The problem occurs whenever I try to position to the left or to the right a panel with the "expand" disabled. If I leave "expand" enabled no problem occurs. Left or right alignment result in the same behaviour.
As shown by the second screenshot, I have now managed to reproduce the bug in a predictable way. I have restored the original configuration running the commands illustrated here (http:// www.watchingthe net.com/ restore- panels- in-ubuntu- back-to- their-default- settings. html), then I modified the top panel (launchbar). The problem occurs whenever I try to position to the left or to the right a panel with the "expand" disabled. If I leave "expand" enabled no problem occurs. Left or right alignment result in the same behaviour.