[lubuntu] Black screen when start

Hello. Suddenly when I started the laptop (Acer TravelMate240, about almost 10 years old) the screen goes black as if the laptop was not connected. It seems to run at first but after several minutes I switch off pressing the on-off button. When started again an option screen appears: Ubuntu GNU Grub version 1.99-21ubuntu3.9. And using the option "Ubuntu linux 3.2.0-40-generic" the problem desapears and the laptop starts correctly. I re-installed Lubuntu from a Live-CD and worked correctly until I downloaded all the updates. And the problem started again. So I suppose the problem is one (or more) of the more than a oen hundred updates downloaded. Am I rigth?
Thanks for your help.