Because WoW is evil.

you all have FAILED! Turns out it works just fine after all

Pssst...it was the leprechauns..

suspects it was a PEBCAK error.

Heh...PEBCAK...

leprechauns are notorious for causing video problems.

PEBKAC

you need to make sure you're not doing dual monitor span. That doesn't work with full screen games. Goto display properties ->settings

if it looks like one giant extra wide monitor, then monitor spanning is turned on, you can turn it off by right clicking on the monitor

you want to switch it to an attached monitor instead! (I've been dual monitoring for about 5 years, it's awesome!)

hahaha, calm down okram, it works fine now

also, I prefer the ID-10-T error