As describe to Lawllipops, my friends laptop is having serious issues. He loads fine, has some lag, nothing ridiculously bad. Can buy items just fine, lanes just fine. However, as soon as an enemy champion hits his screen and my friend attacks, the game starts flickering between two frames. the first frame is half a second after the attack and the 2nd frame is a second later, with no UI. Sounds still work (cannot confirm tower kills or anything like taht though) - when I right click an area of the minimap, I get a confirmation sound from the champion on his computer. Cannot confirm if they actually follow the command, though.
DXDIAG attached, if you need to contact him, just email me or find me on IRC/AIM.