Did you guys remember my last thread, about the bad pixel of brand new iMac 20". After calling to Apple, the gentleman agreed to change to another one, due to the 1 dad pixel defection. So anybody got the similar problem as I found on your iMac, please call Apple immediately to claim it. They will be very nice to solve the problem. Please don't leave one or more bad pixels to stay in the screen and accompany you for another 5 years or so. Thank you for your great helps and comments!