Replying to Pink lines on white background on computer screen? help NS!

Alright, so I don't know very much about computer hardware and monitors and stuff, but lately (past couple of weeks) there's been pink lines running vertically down the screen when there's a white background (like facebook or MS word). Sometimes it's really bad, and sometimes it doesn't even happen. I tried googling it and got some results saying it could be my graphics card, but couldn't really get a sure answer. Hopefully some computer savvy people on here can help!

thanks!