Is the defect the same after you unlock from the screensaver? In other words, if you unlock and navigate to the Home page, do you still see the lower left quadrant, some vertical lines in the middle, and part of the upper right quadrant?
If it's consistent in that way, I would say you have a defective screen and should get a replacement device on warranty. If it's not consistent, I'm not sure what to say. Let us know.
Can you see well enough to do a complete power down and reboot? If so, does that change anything? If it gets better, even only somewhat better, after a reboot, then it may be something other than a bad screen.
If you live anywhere near a B&N store, I think your best bet is to take it in and let them look at it.
