I have a Vaio, and recently, my screen started acting funny. It will display, but not what it should, instead it's a bunch of vertical lines, and when I have it plugged into an external display, it will display on the external, and when I have it set to duplicate display, when ever the screen changes on the external display, the laptop screen will get darker or brighter depending on what I'm looking at.
Are the lines only on the LCD or also on the external display? If only on the LCD, reseat the screen connections. If that does not work, replace the LCD screen. If it's on both external and internal screens, the video card is probably bad and you will need to replace the motherboard. It may be a RAM issue also, but that's rarer, may be cheaper to try different RAM first.