Parece que você tem o gma500.
The problem with 12.04 is that the default kernel included on the desktop CD (all variants) is 3.3.2. This kernel works, but requires some custom boot parameters. Without these parameters you will either get a black screen or distortion.
Switch to a console - Ctrl-Alt-F1 Restart X with 'sudo service lightdm restart'
That should bring you back to a functional graphical desktop, so that you can proceed testing or installing.