WoW -- Black Tear and Random Black Flashing screen

[Multibocks]

Sounds like the setting were too high even though it seems your computer should handle it. Maybe an overheating problem?

[Ughmahedhurtz]

Almost guaranteed that's either a thermal issue on the graphics card or a bad bank of graphics RAM. Drivers can cause that but it's so rare with modern NVidia/ATI solutions that it's usually not worth mentioning.