Triangular glitches on Sims 4

I've just got Sims 4 today and after installing it and trying to run it I found that when I start create a sim or open the menu I end up with triangular glitch shapes across the screen. However when I just leave it sitting after starting the game it is fine.
My sister also has the game and it rund perfectly on her laptop which is the exact same make as mine. Pavilion dv7
I've already ran defrags, uninstalled and re-installed, tried updating all my drivers and looking for patches but nothing has helped. What do I do?
I'm getting exhaspirated as this is a long awaited birthday present that I now cant get to work.