I'm sorry to say but you might have still got the virus again. Often times, even if you don't hit OK it usually does the same thing it would do if you hit cancel.
Next time, I'd advice you hit Alt+F4 to close the window so you have no contact with the window.
As for this lasting very long, this is a serious issue that has to be seen to quickly! This is one reason why an upgrade from vBulletin® Version 3.6.5 to 3.8.1 or if anything please go to 3.7.0.