If you are using a Nvidia graphics card with driver version 196.75, you should be careful:
Blizzard found out, that there is a bug in that video-driver, that has negative effects on your GPU-cooler control.
In the worst case, your video-card is grilled.
They recommend to go back to version 196.21.
The errors show up with WarCraft 3, World of WarCraft or StarCraft 2 Beta.