signed up but cannot log in to the game

Hi I just registered and tried logging in to the game and couldn't. I transferred it off of my mates HDD and reset to default settings no errors occurred during launch of the game as I logged in it got to authenticating and then went straight to non recognized username or password. Recommended wwww.worldofwarcraft.com to fix the issue as well. Not sure if my legit installation is bugging it or what?