Most of the problems you have with nvidia/ATI drivers are due to :
a) Old drivers not updated
b) old drivers dll still in the system
For that do this :
a0) remove all non-essencial kit (microphones, USB devices, etc)
a) download most recent sound and graphics drivers and
http://www.guru3d.com/category/driversweeper/b) uninstall current sound/graphics drivers
c) reboot
d) enter windows in safe mode
e) run
http://www.guru3d.com/category/driversweeper/ and remove everything from Graphics and sound
f) reboot
g) install most recent drivers for sound, graphics.
h) run registry sweeper
i) remove all overclocking from harware
j) check CPU and GPU temperatures
90% of the problems i ever had in over 5 years with several diferent PCs were resolved like this.
