Plz Help Me

alrighty. Ive been having comp problems for a while and had to reinstall my operating system and now everythings better...yea i wish!

After reinstalling WoW, BC, Wotlk and the latest patch, i went to play WoW and a little window popped up (labeled: world of warcraft) and read:

"Failed to find a suitable display device, exiting program"

please help! im suppose to be starting raf with nonamekiller and cant until this is fixxed, plz help