I am aware the nVidia video cards come with an advanced option ... might be to do with FX not sure. But are you able to find it. I have an nVidia 8800 but mine is on a mac uses different software drivers. I was warned by several people over past 12 months about the nVidia advanced options or menu ... this apparently affects some windows users.

Sorry for sounding vague on it. If you find 3D or shaders options, disable them.