This is complicated. I'll try to be concise: Laptop screen stopped working (bottom 1/3 blank). 1st new screen worked BUT had 4 identical quadants (i.e 4 mouse pointers, 4 start buttons, ect). So, I exchanged the screen. 2nd new screen wouldn't work UNTIL (this is the complicated part) I start the laptop with the screen inverter connected to the new screen and the video cable connected to the original screen. After the laptop starts I switch the video cable from the original screen to the new screen and everything works fine (until the laptop hibernates or I turn it off). Laptop works fine with external monitor. What could be causing this? How do I fix it?

It sounds like you are using incompatible screens. Did you verify compatibility before buying?

try updating chiset,graphic drivers then try