What are these green lines that keep on coming every time I start up my PC for the first time?

I suggest you get a new monitor. Try asking LG about it. They might replace it for you for free. I suggest you go on newegg and get something else. Not an LG. Lifes better without it. AKA: Goldstar. Do you have Screen Screw on your pc. Its a software that messes up your screen. Go to the top left corner of your screen to unlock it. If its not that get a new monitor. Don't dump the old one in the trash because you could be fined money. LCD monitors are made of toxic. By the way first try getting some alcohol and cleaning the connectors on the monitor which connects to your VGA or DVI port. Do the same to your Graphics Card. Then get a new VGA or DVI cable and connect it. If that doesn't fix that then trash it. Good Luck