There is a bit issue with updating drivers on Sony Vaio CW (VPCCW1S1E). I am trying to update nvidia drivers on that. It has GT230M gpu on it. I am not able to get the latest driver edition on it. The screen flicker a lot. At first when I tried to download the new driver the same was incomplete. I am doing that through Nvidia Control Panel. There is nothing working. What should I do to fix the problem.