Coloured line distortions on boot up!

Help! I must have done something really bad to my laptop because occasionally while booting up (either restarting or turning on), my laptop's screen will have line distortions all over and it won't load. I have to turn it off and on again a few more times before windows starts and it functions as normal.

I've looked on the internet for help but the closest thing I've found that seems remotely like mine apply to MacBook, whereas mine is an LG laptop.