CyberMania

NVIDIA’s recently released GeForce 196.75 WHQL drivers are causing problems with some users reporting “intermittent low FPS”, in the words of Blizzard’s technical staff. It notes that the drivers have a bug in its fan-speed control that causes graphics cards to overheat when running applications such as Warcraft 3, World of Warcraft and StarCraft 2 Beta. Not only does bad fan control result in bad application performance, but can also damage the graphics accelerator. Blizzard on its part advised users to revert to older versions of the GeForce driver. Version 196.21 (older WHQL-signed driver)

We’re getting reports where users are getting intermittent low FPS after installing these drivers. It seems that it is related to the fan control included in these drivers not working correctly and is causing the video card to overheat on 3D applications. This will affect Warcraft 3, World of Warcraft and StarCraft 2 Beta. Please uninstall the drivers and revert back to the older ones.

Windows XP: http://www.nvidia.com/object/winxp_196.21_whql.html
Windows XP 64-bit: http://www.nvidia.com/object/winxp64_196.21_whql.html
Windows Vista/7 32-bit: http://www.nvidia.com/object/win7_winvista_32bit_196.21_whql.html
Windows Vista/7 64-bit: http://www.nvidia.com/object/win7_winvista_64bit_196.21_whql.html

More information can be found on threads such as these:
http://forums.nvidia.com/index.php?showtopic=161525
http://forums.nvidia.com/index.php?showtopic=161503