I have had the same problem with the nvidia geoforce 8600m gs on my notebook, I have been on every forum trying to find answers and it seems to be the video card is kaput , so there is one answer,I have reinstalled windows vista ,changed memeory sticks tried all types of drivers, I have even seen videos on how to cook your nvidia gpu with some cabbage and onions for ten minutes at 200c to fix it ,will probably try the latter,support does not exist from nvidpia or fujitsu siemens who made my expensive box of frustration, and to boot when fujitsu siemens started getting complaints about their products they went seperate ways ,nvidia points the finger at these two , so as usual its the customer who gets the wrap for buying a faulty...