Quote Originally Posted by 'pengwynman',index.php?page=Thread&postID=155435#p ost155435
Quote Originally Posted by 'Frappuccino',index.php?page=Thread&postID=155397# post155397
I don't think it's the driver as I've tried a couple, though maybe not enough to say for sure. It's definitely not faulty hardware because it only happens when two instances of wow are running at the same time - never when it's just one or any other game.
It could just be too much for my card though...

Out of curiosity Slayer - what vid card was your friend using before and after, and how many instances of wow?
it's certainly possible that your card is having heat issues. any kind of artifact can be caused by excess heat, and this could explain why running 2 instances (= more stress on the system) causes artifacts when one doesn't.
pengwyn hit the nail right on the head. I kept scrolling through the thread to see if anyone mentioned heat.

My very first guess was heat issues. Pre-Shattrath city multiboxing, I played 5 accounts on a Macbook Pro running Windows XP. When it got hot (or I went to an area neat Shattrath that was graphics-intensive), the graphics would start glitching.

The only other thing associated with the problems you're having, which I highly doubt is the case, is a bad DirectX install or unstable video drivers. 99.9999% of drivers and/or DirectX installs that successfully finish installing are just fine, but I guess you could have some weird software glitch going on.