I have the same problem. My computer is a Dell Inspiron 1420, with Ubuntu 12.04 (32 bit) and Nvidia GeForce 8400M GS graphics card (I'm using the recommended drivers).
I have the same problem. My computer is a Dell Inspiron 1420, with Ubuntu 12.04 (32 bit) and Nvidia GeForce 8400M GS graphics card (I'm using the recommended drivers).