I am trying to install Ubuntu 11.04 using a USB drive on a new Lenovo T420s. As soon as the installer tries to load windows manager the display goes blank with thin blue vertical lines covering 1/3rd of the screen from the right.
The USB installer works fine on other non-Lenovo systems.
I hit the same problem. I managed to install ubuntu 11.04 using the alternate install and it mostly works. However sometimes the laptop starts and displays the black screen with vertical strips on 1/3 of the screen (on the right side). I notice that the computer boots and it is awaiting for login but obviously you can't see the screen.
If you push func F4, it goes into sleep and astonishingly, on starting again the screen is restored!
So at the moment I continue using 11.04 and normally carry the laptop in sleep mode. If I stop it and get the vertical lines then I hit fn + f4 and then start so I get the screen back.
This is obviously not ideal, but it is a work arround