I see now that the original Sony Vista drivers are only available in 32 bit: Graphics Driver nVidia - 7.15R - 7.15.11.128 54.45 Mb 17/03/2008. 32 bit
Have you searched the Nvidia site for the latest driver? When you search for GeForce 8400M GT it provides several beta, current and past drivers - one of which may work. I would also first use the auto-detect app: Drivers | GeForce
Well I've just got round to trying the above link you suggested from an earlier post, and surprisingly the first Beta driver worked!
I did try the Nvidia website (UK) where you can search (NVIDIA Driver Downloads - Advanced Search) for drivers, and the same driver that I've just downloaded is listed, but I was apprehensive to download a Beta version.
My Computer
At a glance
Windows 7 Ultimate x64
- Computer type
- Laptop
- Computer Manufacturer/Model Number
- Sony Vaio FZ38M
- OS
- Windows 7 Ultimate x64