My Dell laptop screen was flashing intermittently yesterday, and now it won't even turn on at all. I can still work on it via an external monitor... Once when I started up I got a "memory parity error," but not sure if that relates to this problem. Also, my PC starts up a lot slower than it used to (I hear less "cranking" and just my computer fan running, and the power light is on). Do I need a screen replacement or something? Thanks.