Screen bugs out

Ahoy!
I seem to have this problem with my wotlk wow. Whenever I try to change my video settings so that it'd be windowed mode, a smaller version of wow takes a place on the top left of the screen, which is in front of everything.
Has anyone else had this problem before? I'd love to play the game wiht resolutions matched with the operator I have, but the game simply refuses to work with the idea.
Or is the reason becouse I'm using the new wotlk pack? Should I use the old one instead?

Hey I got the same problem, and I think that's it has to be with the resolution, but I don't know how to fix it so if you already find a solution please let me know